1
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Fernandes L, Kleene R, Congiu L, Freitag S, Kneussel M, Loers G, Schachner M. CHL1 depletion affects dopamine receptor D2-dependent modulation of mouse behavior. Front Behav Neurosci 2023; 17:1288509. [PMID: 38025382 PMCID: PMC10665519 DOI: 10.3389/fnbeh.2023.1288509] [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: 09/04/2023] [Accepted: 10/26/2023] [Indexed: 12/01/2023] Open
Abstract
Introduction The dopaminergic system plays a key role in the appropriate functioning of the central nervous system, where it is essential for emotional balance, arousal, reward, and motor control. The cell adhesion molecule close homolog of L1 (CHL1) contributes to dopaminergic system development, and CHL1 and the dopamine receptor D2 (D2R) are associated with mental disorders like schizophrenia, addiction, autism spectrum disorder and depression. Methods Here, we investigated how the interplay between CHL1 and D2R affects the behavior of young adult male and female wild-type (CHL+/+) and CHL1-deficient (CHL1-/-) mice, when D2R agonist quinpirole and antagonist sulpiride are applied. Results Low doses of quinpirole (0.02 mg/kg body weight) induced hypolocomotion of CHL1+/+ and CHL1-/- males and females, but led to a delayed response in CHL1-/- mice. Sulpiride (1 mg/kg body weight) affected locomotion of CHL1-/- females and social interaction of CHL1+/+ females as well as social interactions of CHL1-/- and CHL1+/+ males. Quinpirole increased novelty-seeking behavior of CHL1-/- males compared to CHL1+/+ males. Vehicle-treated CHL1-/- males and females showed enhanced working memory and reduced stress-related behavior. Discussion We propose that CHL1 regulates D2R-dependent functions in vivo. Deficiency of CHL1 leads to abnormal locomotor activity and emotionality, and to sex-dependent behavioral differences.
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Affiliation(s)
- Luciana Fernandes
- Zentrum für Molekulare Neurobiologie, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany
| | - Ralf Kleene
- Zentrum für Molekulare Neurobiologie, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany
| | - Ludovica Congiu
- Zentrum für Molekulare Neurobiologie, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany
| | - Sandra Freitag
- Institut für Molekulare Neurogenetik, Zentrum für Molekulare Neurobiologie Hamburg, ZMNH, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany
| | - Matthias Kneussel
- Institut für Molekulare Neurogenetik, Zentrum für Molekulare Neurobiologie Hamburg, ZMNH, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany
| | - Gabriele Loers
- Zentrum für Molekulare Neurobiologie, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany
| | - Melitta Schachner
- Department of Cell Biology and Neuroscience, Keck Center for Collaborative Neuroscience, Rutgers University, Piscataway, NJ, United States
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2
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Free RB, Nilson AN, Boldizsar NM, Doyle TB, Rodriguiz RM, Pogorelov VM, Machino M, Lee KH, Bertz JW, Xu J, Lim HD, Dulcey AE, Mach RH, Woods JH, Lane JR, Shi L, Marugan JJ, Wetsel WC, Sibley DR. Identification and Characterization of ML321: A Novel and Highly Selective D 2 Dopamine Receptor Antagonist with Efficacy in Animal Models That Predict Atypical Antipsychotic Activity. ACS Pharmacol Transl Sci 2023; 6:151-170. [PMID: 36654757 PMCID: PMC9841785 DOI: 10.1021/acsptsci.2c00202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Indexed: 12/31/2022]
Abstract
We have developed and characterized a novel D2R antagonist with exceptional GPCR selectivity - ML321. In functional profiling screens of 168 different GPCRs, ML321 showed little activity beyond potent inhibition of the D2R and to a lesser extent the D3R, demonstrating excellent receptor selectivity. The D2R selectivity of ML321 may be related to the fact that, unlike other monoaminergic ligands, ML321 lacks a positively charged amine group and adopts a unique binding pose within the orthosteric binding site of the D2R. PET imaging studies in non-human primates demonstrated that ML321 penetrates the CNS and occupies the D2R in a dose-dependent manner. Behavioral paradigms in rats demonstrate that ML321 can selectively antagonize a D2R-mediated response (hypothermia) while not affecting a D3R-mediated response (yawning) using the same dose of drug, thus indicating exceptional in vivo selectivity. We also investigated the effects of ML321 in animal models that are predictive of antipsychotic efficacy in humans. We found that ML321 attenuates both amphetamine- and phencyclidine-induced locomotor activity and restored pre-pulse inhibition (PPI) of acoustic startle in a dose-dependent manner. Surprisingly, using doses that were maximally effective in both the locomotor and PPI studies, ML321 was relatively ineffective in promoting catalepsy. Kinetic studies revealed that ML321 exhibits slow-on and fast-off receptor binding rates, similar to those observed with atypical antipsychotics with reduced extrapyramidal side effects. Taken together, these observations suggest that ML321, or a derivative thereof, may exhibit ″atypical″ antipsychotic activity in humans with significantly fewer side effects than observed with the currently FDA-approved D2R antagonists.
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Affiliation(s)
- R. Benjamin Free
- Molecular
Neuropharmacology Section, National Institute of Neurological Disorders
and Stroke, Intramural Research Program, National Institutes of Health, 35 Convent Drive, MSC-3723, Bethesda, Maryland20892, United States
| | - Ashley N. Nilson
- Molecular
Neuropharmacology Section, National Institute of Neurological Disorders
and Stroke, Intramural Research Program, National Institutes of Health, 35 Convent Drive, MSC-3723, Bethesda, Maryland20892, United States
| | - Noelia M. Boldizsar
- Molecular
Neuropharmacology Section, National Institute of Neurological Disorders
and Stroke, Intramural Research Program, National Institutes of Health, 35 Convent Drive, MSC-3723, Bethesda, Maryland20892, United States
| | - Trevor B. Doyle
- Molecular
Neuropharmacology Section, National Institute of Neurological Disorders
and Stroke, Intramural Research Program, National Institutes of Health, 35 Convent Drive, MSC-3723, Bethesda, Maryland20892, United States
| | - Ramona M. Rodriguiz
- Department
of Psychiatry and Behavioral Sciences, Mouse Behavioral and Neuroendocrine
Analysis Core Facility, Duke University
Medical Center, 354 Sands Building, 303 Research Drive, Durham, North Carolina27710, United States
| | - Vladimir M. Pogorelov
- Department
of Psychiatry and Behavioral Sciences, Mouse Behavioral and Neuroendocrine
Analysis Core Facility, Duke University
Medical Center, 354 Sands Building, 303 Research Drive, Durham, North Carolina27710, United States
| | - Mayako Machino
- Computational
Chemistry and Molecular Biophysics Section, Molecular Targets and
Medications Discovery Branch, National Institute on Drug Abuse, Intramural
Research Program, National Institutes of
Health, 333 Cassell Drive, Baltimore, Maryland21224, United
States
| | - Kuo Hao Lee
- Computational
Chemistry and Molecular Biophysics Section, Molecular Targets and
Medications Discovery Branch, National Institute on Drug Abuse, Intramural
Research Program, National Institutes of
Health, 333 Cassell Drive, Baltimore, Maryland21224, United
States
| | - Jeremiah W. Bertz
- Department
of Pharmacology, University of Michigan
Medical School, 1150 W. Medical Center Dr., Ann Arbor, Michigan48109, United States
| | - Jinbin Xu
- Division
of Radiological Sciences, Department of Radiology, Mallinckrodt Institute
of Radiology, Washington University School
of Medicine, St. Louis, Missouri63110, United States
| | - Herman D. Lim
- Drug Discovery
Biology, Monash Institute of Pharmaceutical Sciences, Monash University, 399 Royal Parade, Parkville, VIC3052, Australia
| | - Andrés E. Dulcey
- Division
of Pre-Clinical Innovation, National Center for Advancing Translational
Sciences, National Institutes of Health, 9800 Medical Center Drive, Rockville, Maryland20850, United States
| | - Robert H. Mach
- Department
of Radiology, Perelman School of Medicine, University of Pennsylvania, 3400 Civic Center Boulevard, Philadelphia, Pennsylvania19104, United States
| | - James H. Woods
- Department
of Pharmacology, University of Michigan
Medical School, 1150 W. Medical Center Dr., Ann Arbor, Michigan48109, United States
| | - J Robert Lane
- Centre
of Membrane Proteins and Receptors, Universities
of Birmingham and Nottingham, NottinghamNG7 2UH, United Kingdom
| | - Lei Shi
- Computational
Chemistry and Molecular Biophysics Section, Molecular Targets and
Medications Discovery Branch, National Institute on Drug Abuse, Intramural
Research Program, National Institutes of
Health, 333 Cassell Drive, Baltimore, Maryland21224, United
States
| | - Juan J. Marugan
- Division
of Pre-Clinical Innovation, National Center for Advancing Translational
Sciences, National Institutes of Health, 9800 Medical Center Drive, Rockville, Maryland20850, United States
| | - William C. Wetsel
- Department
of Psychiatry and Behavioral Sciences, Mouse Behavioral and Neuroendocrine
Analysis Core Facility, Duke University
Medical Center, 354 Sands Building, 303 Research Drive, Durham, North Carolina27710, United States
- Departments
of Neurobiology and Cell Biology, Duke University
Medical Center, 354 Sands Building, 303 Research Drive, Durham, North Carolina27710, United States
| | - David R. Sibley
- Molecular
Neuropharmacology Section, National Institute of Neurological Disorders
and Stroke, Intramural Research Program, National Institutes of Health, 35 Convent Drive, MSC-3723, Bethesda, Maryland20892, United States
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3
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Wenk D, Khan S, Ignatchenko V, Hübner H, Gmeiner P, Weikert D, Pischetsrieder M, Kislinger T. Phosphoproteomic Analysis of Dopamine D2 Receptor Signaling Reveals Interplay of G Protein- and β-Arrestin-Mediated Effects. J Proteome Res 2023; 22:259-271. [PMID: 36508580 PMCID: PMC9831068 DOI: 10.1021/acs.jproteome.2c00707] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Leveraging biased signaling of G protein-coupled receptors has been proposed as a promising strategy for the development of drugs with higher specificity. However, the consequences of selectively targeting G protein- or β-arrestin-mediated signaling on cellular functions are not comprehensively understood. In this study, we utilized phosphoproteomics to gain a systematic overview of signaling induced by the four biased and balanced dopamine D2 receptor (D2R) ligands MS308, BM138, quinpirole, and sulpiride in an in vitro D2R transfection model. Quantification of 14,160 phosphosites revealed a low impact of the partial G protein agonist MS308 on cellular protein phosphorylation, as well as surprising similarities between the balanced agonist quinpirole and the inverse agonist sulpiride. Analysis of the temporal profiles of ligand-induced phosphorylation events showed a transient impact of the G protein-selective agonist MS308, whereas the β-arrestin-preferring agonist BM138 elicited a delayed, but more pronounced response. Functional enrichment analysis of ligand-impacted phosphoproteins and treatment-linked kinases confirmed multiple known functions of D2R signaling while also revealing novel effects, for example of MS308 on sterol regulatory element-binding protein-related gene expression. All raw data were deposited in MassIVE (MSV000089457).
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Affiliation(s)
- Deborah Wenk
- Princess
Margaret Cancer Centre, University Health
Network, 101 College
Street, Toronto, Ontario M5G 1L7, Canada
| | - Shahbaz Khan
- Princess
Margaret Cancer Centre, University Health
Network, 101 College
Street, Toronto, Ontario M5G 1L7, Canada
| | - Vladimir Ignatchenko
- Princess
Margaret Cancer Centre, University Health
Network, 101 College
Street, Toronto, Ontario M5G 1L7, Canada
| | - Harald Hübner
- Medicinal
Chemistry, Department of Chemistry and Pharmacy, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Nikolaus-Fiebiger-Strasse 10, 91058 Erlangen, Germany
| | - Peter Gmeiner
- Medicinal
Chemistry, Department of Chemistry and Pharmacy, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Nikolaus-Fiebiger-Strasse 10, 91058 Erlangen, Germany
| | - Dorothee Weikert
- Medicinal
Chemistry, Department of Chemistry and Pharmacy, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Nikolaus-Fiebiger-Strasse 10, 91058 Erlangen, Germany
| | - Monika Pischetsrieder
- Food
Chemistry, Department of Chemistry and Pharmacy, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Nikolaus-Fiebiger-Strasse 10, 91058 Erlangen, Germany
| | - Thomas Kislinger
- Princess
Margaret Cancer Centre, University Health
Network, 101 College
Street, Toronto, Ontario M5G 1L7, Canada,Department
of Medical Biophysics, University of Toronto, 101 College Street, Toronto, Ontario M5G 1L7, Canada,
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4
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Frau R, Devoto P, Aroni S, Saba P, Sagheddu C, Siddi C, Santoni M, Carli M, Gessa GL. The potent α 2-adrenoceptor antagonist RS 79948 also inhibits dopamine D 2 -receptors: Comparison with atipamezole and raclopride. Neuropharmacology 2022; 217:109192. [PMID: 35850212 DOI: 10.1016/j.neuropharm.2022.109192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Revised: 07/08/2022] [Accepted: 07/11/2022] [Indexed: 11/16/2022]
Abstract
Neurochemical, electrophysiological and behavioral evidence indicate that the potent α2-adrenoceptor antagonist RS 79948 is also a dopamine (DA) D2 receptor antagonist. Thus, results from ligand binding and adenylate cyclase activity indicate that RS 79948 binds to D2 receptors and antagonized D2 receptor-mediated inhibition of cAMP synthesis at nanomolar concentrations. RESULTS: from microdialysis indicated that RS 79948 shared with the selective α2-adrenergic antagonist atipamezole the ability to increase the co-release of DA and norepinephrine (NE) from noradrenergic terminals in the medial prefrontal cortex (mPFC), except that RS 79948-induced DA release persisted after noradrenergic denervation, unlike atipamezole effect, indicating that RS 79948 releases DA from dopaminergic terminals as well. Similarly to the D2 antagonist raclopride, but unlike atipamezole, RS 79948 increased extracellular DA and DOPAC in the caudate nucleus. Electrophysiological results indicate that RS 79948 shared with raclopride the ability to activate the firing of ventral tegmental area (VTA) DA neurons, while atipamezole was ineffective. RESULTS: from behavioral studies indicated that RS 79948 exerted effects mediated by independent, cooperative and contrasting inhibition of α2-and D2 receptors. Thus, RS 79948, but not atipamezole, prevented D2-autoreceptor mediated hypomotility produced by a small dose of quinpirole. RS 79948 potentiated, more effectively than atipamezole, quinpirole-induced motor stimulation. RS 79948 antagonized, less effectively than atipamezole, raclopride-induced catalepsy. Future studies should clarify if the dual α2-adrenoceptor- and D2-receptor antagonistic action might endow RS 79948 with potential therapeutic relevance in the treatment of schizophrenia, drug dependence, depression and Parkinson's disease.
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Affiliation(s)
- Roberto Frau
- Department of Biomedical Sciences, Section of Neurosciences and Clinical Pharmacology, University of Cagliari, Cittadella Universitaria, Monserrato, CA, Italy; The Guy Everett Laboratory for Neuroscience, University of Cagliari, Cittadella Universitaria, Monserrato, CA, Italy
| | - Paola Devoto
- Department of Biomedical Sciences, Section of Neurosciences and Clinical Pharmacology, University of Cagliari, Cittadella Universitaria, Monserrato, CA, Italy; The Guy Everett Laboratory for Neuroscience, University of Cagliari, Cittadella Universitaria, Monserrato, CA, Italy.
| | - Sonia Aroni
- Department of Biomedical Sciences, Section of Neurosciences and Clinical Pharmacology, University of Cagliari, Cittadella Universitaria, Monserrato, CA, Italy
| | - Pierluigi Saba
- Department of Biomedical Sciences, Section of Neurosciences and Clinical Pharmacology, University of Cagliari, Cittadella Universitaria, Monserrato, CA, Italy
| | - Claudia Sagheddu
- Department of Biomedical Sciences, Section of Neurosciences and Clinical Pharmacology, University of Cagliari, Cittadella Universitaria, Monserrato, CA, Italy
| | - Carlotta Siddi
- Department of Biomedical Sciences, Section of Neurosciences and Clinical Pharmacology, University of Cagliari, Cittadella Universitaria, Monserrato, CA, Italy
| | - Michele Santoni
- Department of Biomedical Sciences, Section of Neurosciences and Clinical Pharmacology, University of Cagliari, Cittadella Universitaria, Monserrato, CA, Italy
| | - Marco Carli
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Italy
| | - Gian Luigi Gessa
- Department of Biomedical Sciences, Section of Neurosciences and Clinical Pharmacology, University of Cagliari, Cittadella Universitaria, Monserrato, CA, Italy; The Guy Everett Laboratory for Neuroscience, University of Cagliari, Cittadella Universitaria, Monserrato, CA, Italy
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5
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Investigating the ligand agonism and antagonism at the D 2long receptor by dynamic mass redistribution. Sci Rep 2022; 12:9637. [PMID: 35688965 PMCID: PMC9187652 DOI: 10.1038/s41598-022-14311-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2022] [Accepted: 06/06/2022] [Indexed: 11/09/2022] Open
Abstract
The signalling of the D2 receptor (D2R), a G protein-coupled receptor (GPCR), is a complex process consisting of various components. For the screening of D2R ligands, methods quantifying distinct second messengers such as cAMP or the interaction of the receptor with β-arrestin, are commonly employed. In contrast, a label-free biosensor technology like dynamic mass redistribution (DMR), where it is mostly unknown how the individual signalling pathways contribute to the DMR signal, provides a holistic readout of the complex cellular response. In this study, we report the successful application of the DMR technology to CHO-K1 cells stably expressing the human dopamine D2long receptor. In real-time kinetic experiments, studies of D2R reference compounds yielded results for agonists and antagonists that were consistent with those obtained by conventional methods and also allowed a discrimination between partial and full agonists. Furthermore, investigations on the signalling pathway in CHO-K1 hD2longR cells identified the Gαi/o protein as the main proximal trigger of the observed DMR response. The present study has shown that the DMR technology is a valuable method for the characterisation of putative new ligands and, due to its label-free nature, suggests its use for deorphanisation studies of GPCRs.
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6
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Ferraiolo M, Atik H, Ponthot R, Belo do Nascimento I, Beckers P, Stove C, Hermans E. Receptor density influences ligand-induced dopamine D 2L receptor homodimerization. Eur J Pharmacol 2021; 911:174557. [PMID: 34626593 DOI: 10.1016/j.ejphar.2021.174557] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 09/03/2021] [Accepted: 09/10/2021] [Indexed: 01/23/2023]
Abstract
Chronic treatments with dopamine D2 receptor ligands induce fluctuations in D2 receptor density. Since D2 receptors tend to assemble as homodimers, we hypothesized that receptor density might influence constitutive and ligand-induced homodimerization. Using a nanoluciferase-based complementation assay to monitor dopamine D2L receptor homodimerization in a cellular model enabling the tetracycline-controlled expression of dopamine D2L receptors, we observed that increasing receptor density promoted constitutive dopamine D2L receptor homodimerization. Receptor full agonists promoted homodimerization, while antagonists and partial agonists disrupted dopamine D2L receptor homodimers. High receptor densities enhanced this inhibitory effect only for receptor antagonists. Taken together, our findings indicate that both receptor density and receptor ligands influence dopamine D2L receptor homodimerization, albeit excluding any strict correlation with ligands' intrinsic activity and highlighting further complexity to dopaminergic pharmacology.
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Affiliation(s)
- Mattia Ferraiolo
- Neuropharmacology Laboratory, Institute of Neuroscience, UCLouvain, Brussels, Belgium
| | - Hicham Atik
- Neuropharmacology Laboratory, Institute of Neuroscience, UCLouvain, Brussels, Belgium
| | - Romane Ponthot
- Neuropharmacology Laboratory, Institute of Neuroscience, UCLouvain, Brussels, Belgium
| | | | - Pauline Beckers
- Neuropharmacology Laboratory, Institute of Neuroscience, UCLouvain, Brussels, Belgium
| | - Christophe Stove
- Laboratory of Toxicology, Department of Bioanalysis, Ghent University, Ghent, Belgium
| | - Emmanuel Hermans
- Neuropharmacology Laboratory, Institute of Neuroscience, UCLouvain, Brussels, Belgium.
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7
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Wenk D, Ignatchenko V, Macklin A, Hübner H, Gmeiner P, Weikert D, Pischetsrieder M, Kislinger T. Functionally selective activation of the dopamine receptor D 2 is mirrored by the protein expression profiles. Sci Rep 2021; 11:3501. [PMID: 33568753 PMCID: PMC7875989 DOI: 10.1038/s41598-021-83038-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Accepted: 01/28/2021] [Indexed: 01/11/2023] Open
Abstract
The development of functionally selective or biased ligands is a promising approach towards drugs with less side effects. Biased ligands for G protein-coupled receptors can selectively induce G protein activation or β-arrestin recruitment. The consequences of this selective action on cellular functions, however, are not fully understood. Here, we investigated the impact of five biased and balanced dopamine D2 receptor agonists and antagonists on the global protein expression in HEK293T cells by untargeted nanoscale liquid chromatography-tandem mass spectrometry. The proteome analysis detected 5290 protein groups. Hierarchical clustering and principal component analysis based on the expression levels of 1462 differential proteins led to a separation of antagonists and balanced agonist from the control treatment, while the biased ligands demonstrated larger similarities to the control. Functional analysis of affected proteins revealed that the antagonists haloperidol and sulpiride regulated exocytosis and peroxisome function. The balanced agonist quinpirole, but not the functionally selective agonists induced a downregulation of proteins involved in synaptic signaling. The β-arrestin-preferring agonist BM138, however, regulated several proteins related to neuron function and the dopamine receptor-mediated signaling pathway itself. The G protein-selective partial agonist MS308 influenced rather broad functional terms such as DNA processing and mitochondrial translation.
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Affiliation(s)
- Deborah Wenk
- Food Chemistry, Department of Chemistry and Pharmacy, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Nikolaus-Fiebiger-Str. 10, 91058, Erlangen, Germany
| | - Vladimir Ignatchenko
- Princess Margaret Cancer Centre, University Health Network, 101 College Street, Toronto, ON, Canada
| | - Andrew Macklin
- Princess Margaret Cancer Centre, University Health Network, 101 College Street, Toronto, ON, Canada
| | - Harald Hübner
- Medicinal Chemistry, Department of Chemistry and Pharmacy, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Nikolaus-Fiebiger-Str. 10, 91058, Erlangen, Germany
| | - Peter Gmeiner
- Medicinal Chemistry, Department of Chemistry and Pharmacy, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Nikolaus-Fiebiger-Str. 10, 91058, Erlangen, Germany
| | - Dorothée Weikert
- Medicinal Chemistry, Department of Chemistry and Pharmacy, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Nikolaus-Fiebiger-Str. 10, 91058, Erlangen, Germany
| | - Monika Pischetsrieder
- Food Chemistry, Department of Chemistry and Pharmacy, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Nikolaus-Fiebiger-Str. 10, 91058, Erlangen, Germany.
| | - Thomas Kislinger
- Princess Margaret Cancer Centre, University Health Network, 101 College Street, Toronto, ON, Canada.,Department of Medical Biophysics, University of Toronto, 101 College Street, Toronto, ON, Canada
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8
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Kotarska A, Fernandes L, Kleene R, Schachner M. Cell adhesion molecule close homolog of L1 binds to the dopamine receptor D2 and inhibits the internalization of its short isoform. FASEB J 2020; 34:4832-4851. [PMID: 32052901 DOI: 10.1096/fj.201900577rrrr] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 12/05/2019] [Accepted: 12/05/2019] [Indexed: 02/05/2023]
Abstract
Cell adhesion molecule close homolog of L1 (CHL1) and the dopamine receptor D2 (DRD2) are associated with psychiatric and mental disorders. We here show that DRD2 interacts with CHL1 in mouse brain, as evidenced by co-immunostaining, proximity ligation assay, co-immunoprecipitation, and pull-down assay with recombinant extracellular CHL1 domain fused to Fc (CHL1-Fc). Direct binding of CHL1-Fc to the first extracellular loop of DRD2 was shown by ELISA. Using HEK cells transfected to co-express CHL1 and the short (DRD2-S) or long (DRD2-L) DRD2 isoforms, co-localization of CHL1 and both isoforms was observed by immunostaining and proximity ligation assay. Moreover, CHL1 inhibited agonist-triggered internalization of DRD2-S. Proximity ligation assay showed close interaction between CHL1 and DRD2 in neurons expressing dopamine- and cAMP-regulated phosphoprotein of 32 kDa (DARPP32) or tyrosine hydroxylase (TH) in tissue sections of adult mouse striatum. In cultures of striatum or ventral midbrain, CHL1 was also closely associated with DRD2 in DARPP32- or TH-immunopositive cells, respectively. In the dorsal striatum of CHL1-deficient mice, lower levels of DRD2 and phosphorylated TH were observed, when compared to wild-type littermates. In the ventral striatum of CHL1-deficient mice, levels of phosphorylated DARPP32 were reduced. We propose that CHL1 regulates DRD2-dependent presynaptic and postsynaptic functions.
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Affiliation(s)
- Agnieszka Kotarska
- Zentrum für Molekulare Neurobiologie, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany
| | - Luciana Fernandes
- Zentrum für Molekulare Neurobiologie, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany
| | - Ralf Kleene
- Zentrum für Molekulare Neurobiologie, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany
| | - Melitta Schachner
- Center for Neuroscience, Shantou University Medical College, Shantou, China
- Keck Center for Collaborative Neuroscience and Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, NJ, USA
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9
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Magli E, Kędzierska E, Kaczor AA, Severino B, Corvino A, Perissutti E, Frecentese F, Saccone I, Massarelli P, Gibuła‐Tarłowska E, Kotlińska JH, Santagada V, Caliendo G, Fiorino F. Synthesis, docking studies, and pharmacological evaluation of 5HT
2C
ligands containing the
N
′‐cyanoisonicotinamidine or
N
′‐cyanopicolinamidine nucleus. Arch Pharm (Weinheim) 2019; 352:e1800373. [DOI: 10.1002/ardp.201800373] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 02/07/2019] [Accepted: 02/09/2019] [Indexed: 01/18/2023]
Affiliation(s)
- Elisa Magli
- Dipartimento di FarmaciaUniversità di Napoli “Federico II”Naples Italy
| | - Ewa Kędzierska
- Department of Pharmacology and Pharmacodynamics, Faculty of Pharmacy with Division of Medical AnalyticsMedical University of LublinLublin Poland
| | - Agnieszka A. Kaczor
- Department of Synthesis and Chemical Technology of Pharmaceutical Substances with Computer Modeling Laboratory, Faculty of Pharmacy with Division of Medical AnalyticsMedical University of LublinLublin Poland
- School of PharmacyUniversity of Eastern FinlandKuopio Finland
| | - Beatrice Severino
- Dipartimento di FarmaciaUniversità di Napoli “Federico II”Naples Italy
| | - Angela Corvino
- Dipartimento di FarmaciaUniversità di Napoli “Federico II”Naples Italy
| | - Elisa Perissutti
- Dipartimento di FarmaciaUniversità di Napoli “Federico II”Naples Italy
| | | | - Irene Saccone
- Dipartimento di FarmaciaUniversità di Napoli “Federico II”Naples Italy
| | - Paola Massarelli
- Dipartimento di Scienze Mediche, Chirurgiche e NeuroscienzeUniversità di SienaSiena Italy
| | - Ewa Gibuła‐Tarłowska
- Department of Pharmacology and Pharmacodynamics, Faculty of Pharmacy with Division of Medical AnalyticsMedical University of LublinLublin Poland
| | - Jolanta H. Kotlińska
- Department of Pharmacology and Pharmacodynamics, Faculty of Pharmacy with Division of Medical AnalyticsMedical University of LublinLublin Poland
| | | | - Giuseppe Caliendo
- Dipartimento di FarmaciaUniversità di Napoli “Federico II”Naples Italy
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10
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de Witte WEA, Versfelt JW, Kuzikov M, Rolland S, Georgi V, Gribbon P, Gul S, Huntjens D, van der Graaf PH, Danhof M, Fernández-Montalván A, Witt G, de Lange ECM. In vitro and in silico analysis of the effects of D 2 receptor antagonist target binding kinetics on the cellular response to fluctuating dopamine concentrations. Br J Pharmacol 2018; 175:4121-4136. [PMID: 30051456 PMCID: PMC6177617 DOI: 10.1111/bph.14456] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Revised: 06/17/2018] [Accepted: 06/25/2018] [Indexed: 12/27/2022] Open
Abstract
Background and Purpose Target binding kinetics influence the time course of the drug effect (pharmacodynamics) both (i) directly, by affecting the time course of target occupancy, driven by the pharmacokinetics of the drug, competition with endogenous ligands and target turnover, and (ii) indirectly, by affecting signal transduction and homeostatic feedback. For dopamine D2 receptor antagonists, it has been hypothesized that fast receptor binding kinetics cause fewer side effects, because part of the dynamics of the dopaminergic system is preserved by displacement of these antagonists. Experimental Approach Target binding kinetics of D2 receptor antagonists and signal transduction after dopamine and D2 receptor antagonist exposure were measured in vitro. These data were integrated by mechanistic modelling, taking into account competitive binding of endogenous dopamine and the antagonist, the turnover of the second messenger cAMP and negative feedback by PDE turnover. Key Results The proposed signal transduction model successfully described the cellular cAMP response for 17 D2 receptor antagonists with widely different binding kinetics. Simulation of the response to fluctuating dopamine concentrations revealed that a significant effect of the target binding kinetics on the dynamics of the signalling only occurs at endogenous dopamine concentration fluctuations with frequencies below 1 min−1. Conclusions and Implications Signal transduction and feedback are important determinants of the time course of drug effects. The effect of the D2 receptor antagonist dissociation rate constant (koff) is limited to the maximal rate of fluctuations in dopamine signalling as determined by the dopamine koff and the cAMP turnover.
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Affiliation(s)
- Wilhelmus E A de Witte
- Department of Pharmacology, Leiden Academic Centre for Drug Research, Leiden, Netherlands
| | - Joost W Versfelt
- Department of Pharmacology, Leiden Academic Centre for Drug Research, Leiden, Netherlands
| | - Maria Kuzikov
- ScreeningPort, Fraunhofer Institute for Molecular Biology and Applied Ecology, Hamburg, Germany
| | - Solene Rolland
- Global Drug Discovery, Bayer Healthcare Pharmaceuticals, Berlin, Germany
| | - Victoria Georgi
- Global Drug Discovery, Bayer Healthcare Pharmaceuticals, Berlin, Germany
| | - Philip Gribbon
- ScreeningPort, Fraunhofer Institute for Molecular Biology and Applied Ecology, Hamburg, Germany
| | - Sheraz Gul
- ScreeningPort, Fraunhofer Institute for Molecular Biology and Applied Ecology, Hamburg, Germany
| | | | - Piet Hein van der Graaf
- Department of Pharmacology, Leiden Academic Centre for Drug Research, Leiden, Netherlands.,QSP, Certara, Canterbury, UK
| | - Meindert Danhof
- Department of Pharmacology, Leiden Academic Centre for Drug Research, Leiden, Netherlands
| | - Amaury Fernández-Montalván
- Global Drug Discovery, Bayer Healthcare Pharmaceuticals, Berlin, Germany.,Servier Research Institute, Croissy-sur-Seine, France
| | - Gesa Witt
- ScreeningPort, Fraunhofer Institute for Molecular Biology and Applied Ecology, Hamburg, Germany
| | - Elizabeth C M de Lange
- Department of Pharmacology, Leiden Academic Centre for Drug Research, Leiden, Netherlands
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11
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Van Cott A, Frericks M, Hastings C, Honarvar N, Flick B, Fabian E, van Ravenzwaay B. Uterine adenocarcinoma in the rat induced by afidopyropen. An analysis of the lesion's induction, progression and its relevance to humans. Regul Toxicol Pharmacol 2018; 95:29-51. [DOI: 10.1016/j.yrtph.2018.02.018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Revised: 01/29/2018] [Accepted: 02/28/2018] [Indexed: 11/16/2022]
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12
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Abstract
Introduction: Providing clinicians with an easy to grasp and understandable representation of pharmacology is important to allow optimal clinical decisions to be made. Two of the most clinically relevant dimensions are receptor binding affinity and functional activity. The binding affinity for an agonist is described by the dissociation constant (KA), and an antagonist by the inhibition constant (Ki). Functionally, medications can act as superagonists, agonists, partial agonists, antagonists, partial inverse agonists, or inverse agonists at several receptor sites, transporters, or ion channels. Comprehending the differences between agents is complicated by the number and types of binding sites. Methods: Binding and functional data are obtained from primary literature, product labels, human cloned receptor binding, and other sources. Binding affinities are converted into ratios relative to the putative primary receptor for that category of agent. Antipsychotic binding is referenced to dopamine type 2 long (D2L) receptor binding. Binding affinity ratios (BARs) generate a 6-spoked diagram, with D2L as the hub. The most avidly bound sites are the spokes, and the disk diameter represents the BAR. Where functional data are available, they are shown as a pie chart shading the binding site's disk. Results: Binding and function diagrams are shown for the antipsychotics where binding data are available and are compared to previous methods of pharmacologic comparisons of antipsychotics. Discussion: Use of graphic models of psychotropic pharmacology improves clinician comprehension and may serve as an aid to improve rational therapeutics and patient outcomes.
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Affiliation(s)
- Stephen R Saklad
- Clinical Professor and Director of Psychiatric Pharmacy, Pharmacotherapy Division, College of Pharmacy, University of Texas at Austin, San Antonio, Texas,
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13
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Kasai RS, Ito SV, Awane RM, Fujiwara TK, Kusumi A. The Class-A GPCR Dopamine D2 Receptor Forms Transient Dimers Stabilized by Agonists: Detection by Single-Molecule Tracking. Cell Biochem Biophys 2017; 76:29-37. [PMID: 29116599 PMCID: PMC5913388 DOI: 10.1007/s12013-017-0829-y] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Accepted: 09/18/2017] [Indexed: 01/06/2023]
Abstract
Whether class-A G-protein coupled receptors (GPCRs) exist and work as monomers or dimers has drawn extensive attention. A class-A GPCR dopamine D2 receptor (D2R) is involved in many physiological and pathological processes and diseases, indicating its critical role in proper functioning of neuronal circuits. In particular, D2R homodimers might play key roles in schizophrenia development and amphetamine-induced psychosis. Here, using single-molecule imaging, we directly tracked single D2R molecules in the plasma membrane at a physiological temperature of 37 °C, and unequivocally determined that D2R forms transient dimers with a lifetime of 68 ms in its resting state. Agonist addition prolonged the dimer lifetime by a factor of ~1.5, suggesting the possibility that transient dimers might be involved in signaling.
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Affiliation(s)
- Rinshi S Kasai
- Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto, 606-8507, Japan
| | - Shuichi V Ito
- Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto, 606-8507, Japan
| | - Ryo M Awane
- Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto, 606-8507, Japan
| | - Takahiro K Fujiwara
- Center for Meso-Bio Single-Molecule Imaging (CeMI), Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Kyoto, 606-8507, Japan
| | - Akihiro Kusumi
- Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto, 606-8507, Japan. .,Center for Meso-Bio Single-Molecule Imaging (CeMI), Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Kyoto, 606-8507, Japan. .,Membrane Cooperativity Unit, Okinawa Institute of Science and Technology, Okinawa, 904-0495, Japan.
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Fiorino F, Magli E, Kędzierska E, Ciano A, Corvino A, Severino B, Perissutti E, Frecentese F, Di Vaio P, Saccone I, Izzo AA, Capasso R, Massarelli P, Rossi I, Orzelska-Gòrka J, Kotlińska JH, Santagada V, Caliendo G. New 5-HT1A, 5HT2A and 5HT2C receptor ligands containing a picolinic nucleus: Synthesis, in vitro and in vivo pharmacological evaluation. Bioorg Med Chem 2017; 25:5820-5837. [DOI: 10.1016/j.bmc.2017.09.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Revised: 09/05/2017] [Accepted: 09/13/2017] [Indexed: 02/02/2023]
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15
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Dopamine D 2 receptors and the circadian clock reciprocally mediate antipsychotic drug-induced metabolic disturbances. NPJ SCHIZOPHRENIA 2017; 3:17. [PMID: 28560263 PMCID: PMC5441531 DOI: 10.1038/s41537-017-0018-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Revised: 03/01/2017] [Accepted: 03/08/2017] [Indexed: 01/11/2023]
Abstract
Antipsychotic drugs are widely prescribed medications, used for numerous psychiatric illnesses. However, antipsychotic drugs cause serious metabolic side effects that can lead to substantial weight gain and increased risk for type 2 diabetes. While individual drugs differ, all antipsychotic drugs may cause these important side effects to varying degrees. Given that the single unifying property shared by these medications is blockade of dopamine D2 and D3 receptors, these receptors likely play a role in antipsychotic drug-induced metabolic side effects. Dopamine D2 and dopamine D3 receptors are expressed in brain regions critical for metabolic regulation and appetite. Surprisingly, these receptors are also expressed peripherally in insulin-secreting pancreatic beta cells. By inhibiting glucose-stimulated insulin secretion, dopamine D2 and dopamine D3 receptors are important mediators of pancreatic insulin release. Crucially, antipsychotic drugs disrupt this peripheral metabolic regulatory mechanism. At the same time, disruptions to circadian timing have been increasingly recognized as a risk factor for metabolic disturbance. Reciprocal dopamine and circadian signaling is important for the timing of appetitive/feeding behaviors and insulin release, thereby coordinating cell metabolism with caloric intake. In particular, circadian regulation of dopamine D2 receptor/dopamine D3 receptor signaling may play a critical role in metabolism. Therefore, we propose that antipsychotic drugs’ blockade of dopamine D2 receptor and dopamine D3 receptors in pancreatic beta cells, hypothalamus, and striatum disrupts the cellular timing mechanisms that regulate metabolism. Ultimately, understanding the relationships between the dopamine system and circadian clocks may yield critical new biological insights into mechanisms of antipsychotic drug action, which can then be applied into clinical practice.
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Design and synthesis of novel N-sulfonyl-2-indoles that behave as 5-HT6 receptor ligands with significant selectivity for D3 over D2 receptors. Bioorg Med Chem 2017; 25:38-52. [DOI: 10.1016/j.bmc.2016.10.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Revised: 10/05/2016] [Accepted: 10/07/2016] [Indexed: 11/30/2022]
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17
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Chen XW, Sun YY, Fu L, Li JQ. Synthesis and pharmacological characterization of novel N -( trans -4-(2-(4-(benzo[ d ]isothiazol-3-yl)piperazin-1-yl)ethyl)cyclohexyl)amides as potential multireceptor atypical antipsychotics. Eur J Med Chem 2016; 123:332-353. [DOI: 10.1016/j.ejmech.2016.07.038] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Revised: 06/29/2016] [Accepted: 07/19/2016] [Indexed: 12/23/2022]
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18
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van Wieringen JP, Michel MC, Janssen HM, Janssen AG, Elsinga PH, Booij J. Agonist signalling properties of radiotracers used for imaging of dopamine D2/3 receptors. EJNMMI Res 2014; 4:53. [PMID: 25977878 PMCID: PMC4422956 DOI: 10.1186/s13550-014-0053-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Accepted: 09/23/2014] [Indexed: 01/11/2023] Open
Abstract
Background Dopamine D2/3 receptor (D2/3R) agonist radiopharmaceuticals are considered superior to antagonists to detect dopamine release, e.g. induced by amphetamines. Agonists bind preferentially to the high-affinity state of the dopamine D2R, which has been proposed as the reason why agonists are more sensitive to detect dopamine release than antagonist radiopharmaceuticals, but this theory has been challenged. Interestingly, not all agonists similarly activate the classic cyclic adenosine mono phosphate (cAMP) and the ?-arrestin-2 pathway, some stimulate preferentially one of these pathways; a phenomenon called biased agonism. Because these pathways can be affected separately by pathologies or drugs (including dopamine releasers), it is important to know how agonist radiotracers act on these pathways. Therefore, we characterized the intracellular signalling of the well-known D2/3R agonist radiopharmaceuticals NPA and PHNO and of several novel D2/3R agonists. Methods cAMP accumulation and ?-arrestin-2 recruitment were measured on cells expressing human D2R. Results All tested agonists showed (almost) full agonism in both pathways. Conclusions The tested D2/3R agonist radiopharmaceuticals did not exhibit biased agonism in vitro. Consequently, it is likely that drugs (including psychostimulants like amphetamines) and/or pathologies that influence the cAMP and/or the ?-arrestin-2 pathway may influence the binding of these radiopharmaceuticals.
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Affiliation(s)
- Jan-Peter van Wieringen
- Department of Nuclear Medicine, Academic Medical Center, University of Amsterdam, Meibergdreef 9, Amsterdam, 1105, AZ, The Netherlands
| | - Martin C Michel
- Department of Pharmacology, Johannes Gutenberg University, Mainz, Germany
| | | | | | - Philip H Elsinga
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Jan Booij
- Department of Nuclear Medicine, Academic Medical Center, University of Amsterdam, Meibergdreef 9, Amsterdam, 1105, AZ, The Netherlands
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Roosterman D. Agonist-dependent and -independent dopamine-1-like receptor signalling differentially regulates downstream effectors. FEBS J 2014; 281:4792-804. [PMID: 25154512 DOI: 10.1111/febs.13018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Revised: 07/25/2014] [Accepted: 08/21/2014] [Indexed: 12/17/2022]
Abstract
De-regulation of energy metabolism by the dopaminergic system is linked to neurological diseases such as schizophrenia and bipolar disorder. Inverse agonists are thought to be more beneficial in treating neurological diseases than neutral antagonists, but only limited experimental data are available regarding the impact of constitutive signalling on energy metabolism. The aim of the present study was to assess the impact of constitutive dopamine-1 receptor (D1R) and dopamine-5 receptor (D5R) signalling on downstream targets in transiently and stably transfected HEK293T cells. The high constitutive activity of D5R was accompanied by increased Na(+)/H(+) exchanger (NHE) activity and accelerated glucose degradation due to increased transcription and translation of the Na, K-ATPase-α3 and NHE-2. Chronic treatment with an agonist increased the mRNA levels of the α2 Na,K-ATPase, NHE-2 and NHE-3. Constitutive D5R activation of a cAMP response element-based reporter was regulated by G protein-coupled receptor kinase 2, but this did not affect the cell-surface abundance of the receptor. Our data suggest that constitutive and agonist-induced activity of D5R differentially regulates the activity and expression of proteins.
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20
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Guo J, Sun X, Yu S. Diastereoselective synthesis of epoxide-fused benzoquinolizidine derivatives using intramolecular domino aza-Michael addition/Darzens reaction. Org Biomol Chem 2014; 12:265-8. [DOI: 10.1039/c3ob42068j] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Affiliation(s)
- Jiajia Guo
- State Key Laboratory of Analytical Chemistry for Life Science, Institute of Chemical Biology and Drug Innovation, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China.
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21
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Zhang B, Albaker A, Plouffe B, Lefebvre C, Tiberi M. Constitutive activities and inverse agonism in dopamine receptors. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2014; 70:175-214. [PMID: 24931197 DOI: 10.1016/b978-0-12-417197-8.00007-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The concept of activation in the absence of agonists has been demonstrated for many GPCRs and is now solidified as one of the principal aspects of GPCR signaling. In this chapter, we review how dopamine receptors demonstrate this ability. Although difficult to prove in vivo due to the presence of endogenous dopamine and lack of subtype-selective inverse agonists and "pure" antagonists (neutral ligands), in vitro assays such as measuring intracellular cAMP, [(35)S]GTPγS binding, and [(3)H]thymidine incorporation have uncovered the constitutive activation of D1- and D2-class receptors. Nevertheless, because of limited and inconsistent findings, the existence of constitutive activity for D2-class receptors is currently not well established. Mutagenesis studies have shown that basal signaling, notably by D1-class receptors, is governed by the collective contributions of transmembrane domains and extracellular/intracellular loops, such as the third extracellular loop, the third intracellular loop, and C-terminal tail. Furthermore, constitutive activities of D1-class receptors are subjected to regulation by kinases. Among the dopamine receptor family, the D5 receptor subtype exhibits a higher basal signaling and bears resemblance to constitutively active mutant forms of GPCRs. The presence of its constitutive activity in vivo and its pathophysiological relevance, with a brief mention of other subtypes, are also discussed.
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Affiliation(s)
- Boyang Zhang
- Ottawa Hospital Research Institute (Neuroscience Program), Ottawa, Ontario, Canada; Departments of Medicine, Cellular & Molecular Medicine, Psychiatry, University of Ottawa, Ottawa, Ontario, Canada
| | - Awatif Albaker
- Ottawa Hospital Research Institute (Neuroscience Program), Ottawa, Ontario, Canada; Departments of Medicine, Cellular & Molecular Medicine, Psychiatry, University of Ottawa, Ottawa, Ontario, Canada
| | - Bianca Plouffe
- Department of Biochemistry, Université de Montréal, Montréal, Québec, Canada; Institut de recherche en immunologie, cancer, Montréal, Québec, Canada
| | - Caroline Lefebvre
- Ottawa Hospital Research Institute (Neuroscience Program), Ottawa, Ontario, Canada; Departments of Medicine, Cellular & Molecular Medicine, Psychiatry, University of Ottawa, Ottawa, Ontario, Canada
| | - Mario Tiberi
- Ottawa Hospital Research Institute (Neuroscience Program), Ottawa, Ontario, Canada; Departments of Medicine, Cellular & Molecular Medicine, Psychiatry, University of Ottawa, Ottawa, Ontario, Canada.
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Vauquelin G, Bostoen S, Vanderheyden P, Seeman P. Clozapine, atypical antipsychotics, and the benefits of fast-off D2 dopamine receptor antagonism. Naunyn Schmiedebergs Arch Pharmacol 2012; 385:337-72. [PMID: 22331262 DOI: 10.1007/s00210-012-0734-2] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Accepted: 01/25/2012] [Indexed: 12/20/2022]
Abstract
Drug-receptor interactions are traditionally quantified in terms of affinity and efficacy, but there is increasing awareness that the drug-on-receptor residence time also affects clinical performance. While most interest has hitherto been focused on slow-dissociating drugs, D(2) dopamine receptor antagonists show less extrapyramidal side effects but still have excellent antipsychotic activity when they dissociate swiftly. Fast dissociation of clozapine, the prototype of the "atypical antipsychotics", has been evidenced by distinct radioligand binding approaches both on cell membranes and intact cells. The surmountable nature of clozapine in functional assays with fast-emerging responses like calcium transients is confirmatory. Potential advantages and pitfalls of the hitherto used techniques are discussed, and recommendations are given to obtain more precise dissociation rates for such drugs. Surmountable antagonism is necessary to allow sufficient D(2) receptor stimulation by endogenous dopamine in the striatum. Simulations are presented to find out whether this can be achieved during sub-second bursts in dopamine concentration or rather during much slower, activity-related increases thereof. While the antagonist's dissociation rate is important to distinguish between both mechanisms, this becomes much less so when contemplating time intervals between successive drug intakes, i.e., when pharmacokinetic considerations prevail. Attention is also drawn to the divergent residence times of hydrophobic antagonists like haloperidol when comparing radioligand binding data on cell membranes with those on intact cells and clinical data.
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Affiliation(s)
- Georges Vauquelin
- Department of Molecular and Biochemical Pharmacology, Vrije Universiteit Brussel, Pleinlaan 2, 1050, Brussels, Belgium.
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Pharmacological, neurochemical, and behavioral profile of JB-788, a new 5-HT1A agonist. Neuroscience 2010; 169:1337-46. [PMID: 20580787 DOI: 10.1016/j.neuroscience.2010.05.040] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2010] [Revised: 05/12/2010] [Accepted: 05/16/2010] [Indexed: 11/21/2022]
Abstract
A novel pyridine derivative, 8-{4-[(6-methoxy-2,3-dihydro-[1,4]dioxino[2,3-b]pyridine-3-ylmethyl)-amino]-butyl}-8-aza-spiro[4.5]decane-7,9-dione hydrochloride, termed JB-788, was designed to selectively target 5-HT(1A) receptors. In the present study, the pharmacological profile of JB-788 was characterized in vitro using radioligands binding tests and in vivo using neurochemical and behavioural experiments. JB-788 bound tightly to human 5-HT(1A) receptor expressed in human embryonic kidney 293 (HEK-293) cells with a K(i) value of 0.8 nM. Its binding affinity is in the same range as that observed for the (+/-)8-OH-DPAT, a reference 5HT(1A) agonist compound. Notably, JB-788 only bound weakly to 5-HT(1B) or 5-HT(2A) receptors and moreover the drug displayed only weak or indetectable binding to muscarinic, alpha(2), beta(1) and beta(2) adrenergic receptors, or dopaminergic D(1) receptors. JB-788 was found to display substantial binding affinity for dopaminergic D(2) receptors and, to a lesser extend to alpha(1) adrenoreceptors. JB-788 dose-dependently decreased forskolin-induced cAMP accumulation in HEK cells expressing human 5-HT(1A), thus acting as a potent 5-HT(1A) receptor agonist (E(max.) 75%, EC(50) 3.5 nM). JB-788 did not exhibit any D(2) receptor agonism but progressively inhibited the effects of quinpirole, a D(2) receptor agonist, in the cAMP accumulation test with a K(i) value of 250 nM. JB-788 induced a weak change in cAMP levels in mouse brain but, like some antipsychotics, transiently increased glycogen contents in various brain regions. Behavioral effects were investigated in mice using the elevated plus-maze. JB-788 was found to increase the time duration spent by animals in anxiogenic situations. Locomotor hyperactivity induced by methamphetamine in mouse, a model of antipsychotic activity, was dose-dependently inhibited by JB-788. Altogether, these results suggest that JB-788 displays pharmacological properties, which could be of interest in the area of anxiolytic and antipsychotic drugs.
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Hudson BD, Hébert TE, M. Kelly ME. Ligand- and Heterodimer-Directed Signaling of the CB1 Cannabinoid Receptor. Mol Pharmacol 2009; 77:1-9. [DOI: 10.1124/mol.109.060251] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
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Costentin J. Une nouvelle approche de la prise en charge de la schizophrénie : les agonistes partiels des récepteurs D2 de la dopamine. ANNALES PHARMACEUTIQUES FRANÇAISES 2009; 67:310-9. [DOI: 10.1016/j.pharma.2009.05.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2008] [Accepted: 05/25/2009] [Indexed: 10/20/2022]
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Lee PH. Label-free optical biosensor: A tool for G protein-coupled receptors pharmacology profiling and inverse agonists identification. J Recept Signal Transduct Res 2009; 29:146-53. [DOI: 10.1080/10799890903064390] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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Sánchez-Wandelmer J, Hernández-Pinto AM, Cano S, Dávalos A, de la Peña G, Puebla-Jiménez L, Arilla-Ferreiro E, Lasunción MA, Busto R. Effects of the antipsychotic drug haloperidol on the somastostatinergic system in SH-SY5Y neuroblastoma cells. J Neurochem 2009; 110:631-40. [PMID: 19457089 DOI: 10.1111/j.1471-4159.2009.06159.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Antipsychotics are established drugs in schizophrenia treatment which, however, are not free of side effects. Lipid rafts are critical for normal brain function. Several G protein-coupled receptors, such as somatostatin (SRIF) receptors, have been shown to localize to lipid rafts. The aim of this study was to investigate whether haloperidol treatment affects the composition and functionality of lipid rafts in SH-SY5Y neuroblastoma cells. Haloperidol inhibited cholesterol biosynthesis, leading to a marked reduction in cell cholesterol content and to an accumulation of sterol intermediates, particularly cholesta-8,14-dien-3beta-ol. These changes were accompanied by a loss of flotillin-1 and Fyn from the lipid rafts. We next studied the functionality of the SRIF receptor. Treatment with haloperidol reduced the inhibitory effect of SRIF on adenylyl cyclase (AC) activity. On the other side, haloperidol decreased basal AC activity but increased forskolin-stimulated AC activity. Addition of free cholesterol to the culture medium abrogated the effects of haloperidol on lipid raft composition and SRIF signaling whereas the AC response to forskolin remained elevated. The results show that haloperidol, by affecting cholesterol homeostasis, ultimately alters SRIF signaling and AC activity, which might have physiological consequences.
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Costentin J. Nouvelle stratégie pharmacologique dans la schizophrénie : les agonistes partiels des récepteurs dopaminergiques D2. Caractéristiques principales de l’aripiprazole. Encephale 2009; 35:66-72. [DOI: 10.1016/j.encep.2008.12.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2008] [Accepted: 12/02/2008] [Indexed: 10/21/2022]
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Lee PH, Gao A, van Staden C, Ly J, Salon J, Xu A, Fang Y, Verkleeren R. Evaluation of dynamic mass redistribution technology for pharmacological studies of recombinant and endogenously expressed g protein-coupled receptors. Assay Drug Dev Technol 2008; 6:83-94. [PMID: 18336088 DOI: 10.1089/adt.2007.126] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The Epic cell assay technology (Corning Inc., Corning, NY) uses a resonant waveguide grating optical biosensor to measure cellular response to ligands manifested through dynamic mass redistribution (DMR) of cellular contents. The DMR measurement is a noninvasive, label-free assay that can be used to assess the pharmacological properties of compounds. In this study, a panel of 12 compounds was evaluated against two G protein-coupled receptor (GPCR) targets in recombinant expressed cell lines using the Corning Epic system in 384-well microplates. The evaluation was performed in a double-blinded fashion such that the identity and properties of both the GPCR targets and compounds were unknown to the researchers at the time of the study. Analysis of the DMR response from cell stimulation was used to identify compounds that functioned as agonists or antagonists and to evaluate the associated efficacy and potency. DMR results were shown to have good agreement with data obtained from cyclic AMP and calcium flux assays for compounds evaluated. A further analysis was performed and successfully identified the signaling pathways that the two GPCRs activated. In addition, the DMR measurement was able to detect responses from an endogenous receptor in these cells. The Epic DMR technology provides a generic platform amenable to pharmacological evaluation of cellular responses to GPCR activation in a label-free live cell assay format.
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Affiliation(s)
- Paul H Lee
- Chemistry Research and Discovery, Amgen Inc., Thousand Oaks, California, USA
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Costentin J. Modulations pharmacologiques des systèmes dopaminergiques : des neuroleptiques à l’aripiprazole. Encephale 2007. [DOI: 10.1016/s0013-7006(07)78663-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Heusler P, Newman-Tancredi A, Loock T, Cussac D. Antipsychotics differ in their ability to internalise human dopamine D2S and human serotonin 5-HT1A receptors in HEK293 cells. Eur J Pharmacol 2007; 581:37-46. [PMID: 18190908 DOI: 10.1016/j.ejphar.2007.11.046] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2007] [Revised: 11/13/2007] [Accepted: 11/21/2007] [Indexed: 10/22/2022]
Abstract
Antipsychotic drugs act preferentially via dopamine D(2) receptor blockade, but interaction with serotonin 5-HT(1A) receptors has attracted interest as additional target for antipsychotic treatment. As receptor internalisation is considered crucial for drug action, we tested the propensity of antipsychotics to internalise human (h)D(2S) receptors and h5-HT(1A) receptors. Agonist-induced internalisation of hemaglutinin (HA)-tagged hD(2S) and HA-h5-HT(1A) receptors expressed in HEK293 cells was increased by coexpression of G-protein coupled receptor kinase 2 and beta-arrestin2. At the HA-hD(2S) receptor, dopamine, quinpirole and bromocriptine behaved as full agonists, while S(-)-3-(3-hydroxyphenyl)-N-n-propylpiperidine [(-)-3PPP] and sarizotan were partial agonists. The typical antipsychotic, haloperidol, and the atypical compounds, olanzapine, nemonapride, ziprasidone and clozapine did not internalise HA-hD(2S) receptors, whereas aripiprazole potently internalised these receptors (>50% relative efficacy). Among antipsychotics with combined D(2)/5-HT(1A) properties, bifeprunox and (3-exo)-8-benzoyl-N-[[(2S)7-chloro-2,3-dihydro-1,4-benzodioxin-1-yl]methyl]-8-azabicyclo-[3.2.1]octane-3-methanamine (SSR181507) partially internalised HA-hD(2S) receptors, piperazine, 1-(2,3-dihydro-1,4-benzodioxin-5-yl)-4-[[5-(4-fluorophenyl)-3-pyridinyl]methyl (SLV313) and N-[(2,2-dimethyl-2,3-dihydro-benzofuran-7-yloxy)ethyl]-3-(cyclopent-1-enyl)-benzylamine (F15063) were inactive. At the HA-h5-HT(1A) receptor, serotonin, (+)-8-hydroxy-2-(di-n-propylamino)tetralin [(+)-8-OH-DPAT] and sarizotan were full agonists, buspirone acted as partial agonist. (-)-Pindolol showed little activity and no internalising properties were manifested for the 5-HT(1A) receptor antagonist N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]-ethyl]-N-(2-pyridinyl)cyclohexanecarboxamide (WAY100635). Most antipsychotics induced HA-h5-HT(1A) receptor internalisation, with an efficacy rank order: nemonapride>F15063>SSR181507>bifeprunox approximately SLV313 approximately ziprasidone>aripiprazole and potencies: SLV313>SSR181507 approximately F15063>bifeprunox approximately nemonapride approximately aripiprazole>ziprasidone. Interestingly, the internalisation induced by clozapine was only minimal, whereas aripirazole and bifeprunox were more potent for internalisation than for G-protein activation. These different profiles of antipsychotics for receptor internalisation may help to evaluate their potential therapeutic impact in the treatment of schizophrenia.
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Affiliation(s)
- Peter Heusler
- Cellular and Molecular Biology Department, Pierre Fabre Research Center, F-81106 Castres, France.
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Clark MC, Khan R, Baro DJ. Crustacean dopamine receptors: localization and G protein coupling in the stomatogastric ganglion. J Neurochem 2007; 104:1006-19. [PMID: 17986222 DOI: 10.1111/j.1471-4159.2007.05029.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Neuromodulators, such as dopamine (DA), control motor activity in many systems. To begin to understand how DA modulates motor behaviors, we study a well-defined model: the crustacean stomatogastric nervous system (STNS). The spiny lobster STNS receives both neuromodulatory and neurohormonal dopaminergic input, and extensive background information exists on the cellular and network effects of DA. However, there is a void of information concerning the mechanisms of DA signal transduction in this system. In this study, we show that Gs, Gi, and Gq are activated in response to DA in STNS membrane preparations from five crustacean species representing distant clades in the order Decapoda. Three evolutionarily conserved DA receptors mediate this response in spiny lobsters: D(1alphaPan), D(1betaPan) and D(2alphaPan). G protein coupling for these receptors can vary with the cell type. In the native membrane, the D(1alphaPan) receptor couples with Gs and Gq, the D(1betaPan) receptor couples with Gs, and the D(2alphaPan) receptor couples with Gi. All three receptors are localized exclusively to the synaptic neuropil and most likely generate global biochemical signals that alter ion channels in distant compartments, as well as local signals.
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Affiliation(s)
- Merry C Clark
- Program for Cell and Molecular Biology and Physiology, Department of Biology, Georgia State University, Atlanta, Georgia, USA
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34
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Smit MJ, Vischer HF, Bakker RA, Jongejan A, Timmerman H, Pardo L, Leurs R. Pharmacogenomic and Structural Analysis of Constitutive G Protein–Coupled Receptor Activity. Annu Rev Pharmacol Toxicol 2007; 47:53-87. [PMID: 17029567 DOI: 10.1146/annurev.pharmtox.47.120505.105126] [Citation(s) in RCA: 145] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
G protein-coupled receptors (GPCRs) respond to a chemically diverse plethora of signal transduction molecules. The notion that GPCRs also signal without an external chemical trigger, i.e., in a constitutive or spontaneous manner, resulted in a paradigm shift in the field of GPCR pharmacology. The discovery of constitutive GPCR activity and the fact that GPCR binding and signaling can be strongly affected by a single point mutation drew attention to the evolving area of GPCR pharmacogenomics. For a variety of GPCRs, point mutations have been convincingly linked to human disease. Mutations within conserved motifs, known to be involved in GPCR activation, might explain the properties of some naturally occurring, constitutively active GPCR variants linked to disease. In this review, we provide a brief historical introduction to the concept of constitutive receptor activity and the pharmacogenomic and structural aspects of constitutive receptor activity.
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Affiliation(s)
- Martine J Smit
- Leiden/Amsterdam Center for Drug Research, Division of Medicinal Chemistry, Vrije Universiteit, Faculty of Sciences, Department of Chemistry, 1081 HV Amsterdam, The Netherlands.
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Heusler P, Newman-Tancredi A, Castro-Fernandez A, Cussac D. Differential agonist and inverse agonist profile of antipsychotics at D2L receptors coupled to GIRK potassium channels. Neuropharmacology 2007; 52:1106-13. [PMID: 17239906 DOI: 10.1016/j.neuropharm.2006.11.008] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2006] [Revised: 10/24/2006] [Accepted: 11/27/2006] [Indexed: 11/23/2022]
Abstract
The D(2) dopaminergic receptor represents a major target of antipsychotic drugs. Using the coupling of the human D(2long) (hD(2L)) receptor to G protein-coupled inward rectifier potassium (GIRK) channels in Xenopus laevis oocytes, we examined the activity of antipsychotic agents of different classes - typical, atypical, and a "new generation" of compounds, exhibiting a preferential D(2) and 5-HT(1A) receptor profile. When the hD(2L) receptor was coexpressed with GIRK channels, a series of reference compounds exhibited full agonist (dopamine, and quinpirole), partial agonist (apomorphine, (-)3-PPP, and (+)-UH232) or inverse agonist (raclopride, and L741626) properties. Sarizotan exhibited only very weak partial agonist action. At higher levels of receptor cRNA injected per oocyte, both partial agonist activity and inverse agonist properties were generally more pronounced. The inverse agonist action of L741626 was reversed by interaction with sarizotan, thus confirming the constitutive activity of wild-type hD(2L) receptors in the oocyte expression system. When antipsychotic agents were tested for their actions at the hD(2L) receptor, typical (haloperidol) as well as atypical (nemonapride, ziprasidone, and clozapine) compounds acted as inverse agonists. In contrast, among D(2)/5-HT(1A) antipsychotics, only SLV313 and F15063 behaved as inverse agonists, whilst the other members of this group (bifeprunox, SSR181507 and the recently marketed antipsychotic, aripiprazole) exhibited partial agonist properties. Thus, the X. laevis oocyte expression system highlights markedly different activity of antipsychotics at the hD(2L) receptor. These differential properties may translate to distinct therapeutic potential of these compounds.
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Affiliation(s)
- Peter Heusler
- Cellular and Molecular Biology Department, Pierre Fabre Research Center, 17 Avenue Jean Moulin, 81106 Castres Cedex, France.
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36
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Humbert-Claude M, Morisset S, Gbahou F, Arrang JM. Histamine H3 and dopamine D2 receptor-mediated [35S]GTPgamma[S] binding in rat striatum: evidence for additive effects but lack of interactions. Biochem Pharmacol 2007; 73:1172-81. [PMID: 17306767 DOI: 10.1016/j.bcp.2007.01.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2006] [Revised: 12/19/2006] [Accepted: 01/03/2007] [Indexed: 11/28/2022]
Abstract
The interactions in the rat striatum between H(3) receptors (H(3)Rs) and D(2) receptors (D(2)Rs) were investigated with the [(35)S]GTPgamma[S] binding assay. The H(3)R agonist (R)alpha-methylhistamine increased [(35)S]GTPgamma[S] binding to striatal membranes with an EC(50)=14+/-5 nM and a maximal effect of +19+/-1%. This effect was inhibited by the H(3)R antagonist ciproxifan with a K(i)=1.0+/-0.3 nM. The D(2)R agonist quinpirole increased [(35)S]GTPgamma[S] binding to the same membranes with an EC(50)=1.5+/-0.5 microM and a maximal effect of +28+/-2%. Its effect was blocked by haloperidol with a K(i)=0.3+/-0.1 nM. The maximal effects of the H(3)R and D(2)R agonists were additive (+46+/-3%). However, D(2)R ligands did not modify the effects of H(3)R ligands and vice versa. Ciproxifan behaved as an H(3)R inverse agonist and decreased [(35)S]GTPgamma[S] binding. Haloperidol had no effect and did not change the inverse agonist effect of ciproxifan. Administrations for 10 days of ciproxifan (1.5mg/kg/day) or haloperidol (0.5mg/kg/day) did not change the effects of quinpirole and (R)alpha-methylhistamine, respectively. These data suggest that striatal H(3)Rs and D(2)Rs do not interact through their coupling to G-proteins. However, a hyperactivity of histaminergic and dopaminergic neurons being observed in schizophrenia, the additive activations of H(3)Rs and D(2)Rs suggest that they cooperate to generate some schizophrenic symptoms. Such a postsynaptic mechanism may underlie the antipsychotic-like effects of H(3)R inverse agonists and supports their therapeutic interest, alone or as adjunctive treatment with neuroleptics.
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Affiliation(s)
- Marie Humbert-Claude
- INSERM, Unité de Neurobiologie et Pharmacologie Moléculaire (U573), Centre Paul Broca, 75014 Paris, France
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Chiasson K, Daoust B, Levesque D, Martinoli MG. Dopamine D2 agonists, bromocriptine and quinpirole, increase MPP+ -induced toxicity in PC12 cells. Neurotox Res 2006; 10:31-42. [PMID: 17000468 DOI: 10.1007/bf03033332] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Dopaminergic cell loss in the mesencephalic substantia nigra is the hallmark of Parkinson's disease and may be associated with abnormal oxidative metabolic activity. However, the delicate balance underlying dopamine decline and oxidative stress is still a matter of debate. The aim of this study was to analyze the possible modulation of D2 agonists and antagonists on MPP+ (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridinium ion) -induced cellular death in differentiated and undifferentiated PC12 cells. Using colorimetric assays, western blots and reverse transcriptase-PCR, we demonstrated that two D2 agonists, bromocriptine and quinpirole, consistently increased MPP+ -induced cytotoxicity in both differentiated and undifferentiated PC12 cells, whereas D2 antagonists do not modulate cell death. However, this increase in cellular death was reversed when bromocriptine or quinpirole were used in presence of D2 antagonists. On the other hand, 1-{2-[bis-(4-fluorophenyl)methoxy]ethyl}-4-(3-phenylpropyl)piperazine (GBR 12909), a potent inhibitor of the dopamine transporter, partially reversed MPP+ -induced cellular death and completely abolished the increase of cellular death induced by bromocriptine. Dopamine agonists and antagonists also modulate the expression of the dopamine transporter in PC12 cells; in particular, bromocriptine may alter MPP+ uptake by increasing DAT expression We also show that, in our cellular paradigm, D2 receptor mRNA levels are more abundant that D3 mRNA levels and MPP+ and /or bromocriptine could not modulate D2 gene expression while D3 gene expression clearly decrease after MPP+ and /or bromocriptine treatment.
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Affiliation(s)
- Keith Chiasson
- Department of Biochemistry and Groupe de Recherche en Neurosciences, Université du Québec á Trois-Riviéres, Trois-Riviéres, Québec, Canada
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Dopamine D2 receptor-mediated G protein activation assessed by agonist-stimulated [35S]guanosine 5'-O-(gamma-thiotriphosphate) binding in rat striatal membranes. Prog Neuropsychopharmacol Biol Psychiatry 2006; 30:1304-12. [PMID: 16824659 DOI: 10.1016/j.pnpbp.2006.05.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2006] [Revised: 05/09/2006] [Accepted: 05/09/2006] [Indexed: 11/29/2022]
Abstract
In order to investigate the functional interaction between the native dopamine receptors and their coupled guanine nucleotide-binding regulatory (G) proteins, dopamine-stimulated [(35)S]guanosine 5'-O-(gamma-thiotriphosphate) ([(35)S]GTPgammaS) binding was pharmacologically characterized in rat striatal membranes. Following optimizing the experimental conditions as to the concentrations of GDP, MgCl(2) and NaCl in the assay medium, the agonist and antagonist properties for a series of dopamine receptor ligands were determined mainly under the standard assay condition. The pharmacological profile of this response clearly indicated the involvement of dopamine D(2)-like receptors, but not of dopamine D(1)-like receptors. Among the types of dopamine D(2)-like receptors, dopamine D(2) receptors most likely appeared to be involved in dopamine-stimulated [(35)S]GTPgammaS binding in rat striatal membranes, because the affinities of agonists and antagonists determined in the present study were significantly correlated with those reported in the previous literature only for dopamine D(2) receptors, but not for dopamine D(3) or D(4) types. Though the concentration-dependent inhibition curves of dopamine-stimulated [(35)S]GTPgammaS binding by spiperone and S(-)-raclopride were apparently biphasic, the origin of the low-affinity minor components was not fully determined. The antiparkinsonian drugs with the properties of dopamine receptor agonism were shown to behave as stimulants with varied affinities and relative efficacies in the current assay system. On the other hand, neither phencyclidine (PCP) nor ketamine stimulated the specific [(35)S]GTPgammaS binding, in contrast with the previous report demonstrating that these two N-methyl-D-aspartic acid (NMDA) receptor antagonists behaved as agonists at human dopamine D(2) receptors expressed in Chinese hamster ovary (CHO) cells. These results provide important information about the functional activation of G proteins coupled with dopamine D(2) receptors as well as agonist actions of various compounds at native dopamine D(2) receptors, which are potentially involved in pathophysiology and pharmacotherapy of neuropsychiatric diseases such as Parkinson's disease, schizophrenia and depression.
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Boeckler F, Gmeiner P. The structural evolution of dopamine D3 receptor ligands: structure-activity relationships and selected neuropharmacological aspects. Pharmacol Ther 2006; 112:281-333. [PMID: 16905195 DOI: 10.1016/j.pharmthera.2006.04.007] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2006] [Accepted: 04/13/2006] [Indexed: 01/13/2023]
Abstract
"Evolution consists largely of molecular tinkering."-Following the famous concept of the molecular geneticist and medicine Nobel laureate François Jacob, in this review we describe the structural evolution of dopamine D3 receptor ligands from the natural agonist dopamine (DA) to highly potent and subtype selective new agents by bioisosteric tinkering with well-established and privileged or novel and fancy chemical functionalities and scaffolds. Some of the more than 200 ligands presented herein have already achieved therapeutic or scientific value up to now, some will most likely achieve it in the future. Hence, great importance is not only attached to the relationship between structure and activity of the ligands, but also to their utility as pharmacological tools in animal models or as therapeutics in patients with neurological diseases or other disorders.
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Affiliation(s)
- Frank Boeckler
- Department of Medicinal Chemistry, Emil Fischer Center, Friedrich-Alexander University Erlangen-Nürnberg, Schuhstrasse 19, 91052 Erlangen, Germany.
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40
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Bond RA, Ijzerman AP. Recent developments in constitutive receptor activity and inverse agonism, and their potential for GPCR drug discovery. Trends Pharmacol Sci 2006; 27:92-6. [PMID: 16406086 DOI: 10.1016/j.tips.2005.12.007] [Citation(s) in RCA: 179] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2005] [Revised: 11/21/2005] [Accepted: 12/15/2005] [Indexed: 11/18/2022]
Abstract
The concept of constitutively active G-protein-coupled receptors is now firmly rooted in receptor pharmacology. Many independent research groups have contributed to its acceptance since its introduction by Costa and Herz in 1989. This concept necessitated a revised ligand classification, and a new category of inverse agonists was introduced alongside existing agonist and antagonist ligands. Initially, it was hoped that new therapeutic modalities would become available. However, the drug industry has not adopted inverse agonism as a design criterion and instead accepted that some compounds emerge as (neutral) antagonists in compound screening, whereas other compounds possess inverse agonistic activity. In this article, we summarize aspects of the impact of constitutive activity on the drug-discovery process: for example, its use in orphan receptor assays, its link with pharmacogenetics and genomics, and its relevance for currently marketed drugs.
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Affiliation(s)
- Richard A Bond
- Department of Pharmacological and Pharmaceutical Sciences, University of Houston, 4800 Calhoun, Houston, TX 77204-5037, USA
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41
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Guo W, Shi L, Filizola M, Weinstein H, Javitch JA. Crosstalk in G protein-coupled receptors: changes at the transmembrane homodimer interface determine activation. Proc Natl Acad Sci U S A 2005; 102:17495-500. [PMID: 16301531 PMCID: PMC1287488 DOI: 10.1073/pnas.0508950102] [Citation(s) in RCA: 245] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Functional crosstalk between G protein-coupled receptors in a homo- or heterodimeric assembly likely involves conformational changes at the dimer interface, but the nature of this interface is not yet established, and the dynamic changes have not yet been identified. We have mapped the homodimer interface in the dopamine D2 receptor over the entire length of the fourth transmembrane segment (TM4) by crosslinking of substituted cysteines. Their susceptibilities to crosslinking are differentially altered by the presence of agonists and inverse agonists. The TM4 dimer interface in the inverse agonist-bound conformation is consistent with the dimer of the inactive form of rhodopsin modeled with constraints from atomic force microscopy. Crosslinking of a different set of cysteines in TM4 was slowed by inverse agonists and accelerated in the presence of agonists; crosslinking of the latter set locks the receptor in an active state. Thus, a conformational change at the TM4 dimer interface is part of the receptor activation mechanism.
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Affiliation(s)
- Wen Guo
- Center for Molecular Recognition, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA
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42
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Lu XH, Dwyer DS. Second-generation antipsychotic drugs, olanzapine, quetiapine, and clozapine enhance neurite outgrowth in PC12 cells via PI3K/AKT, ERK, and pertussis toxin-sensitive pathways. J Mol Neurosci 2005; 27:43-64. [PMID: 16055946 DOI: 10.1385/jmn:27:1:043] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2004] [Accepted: 01/26/2005] [Indexed: 11/11/2022]
Abstract
Second-generation antipsychotic drugs, olanzapine, quetiapine, and clozapine, were found to enhance neurite outgrowth induced by nerve growth factor (NGF) in PC12 cells. These drugs increased the number of cells bearing neurites, the length of primary neurites, and the size of the cell body of NGF-differentiated PC12 cells. In addition, the drugs induced sprouting of neurite-like processes in PC12 cells in the absence of NGF. Olanzapine, quetiapine, and clozapine enhanced the phosphorylation of Akt and ERK in combination with NGF, and specific inhibitors of these pathways attenuated these effects. Pretreatment of cells overnight with pertussis toxin had no effect on NGF-induced differentiation but significantly decreased the effects of the antipsychotic drugs on neurite outgrowth, suggesting that Gi/Go-coupled receptors are involved in the response to drug. A better understanding of the mechanisms underlying the effects of the second-generation drugs might suggest new therapeutic targets for enhancement of neurite outgrowth.
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Affiliation(s)
- Xiao-Hong Lu
- Department of Pharmacology, Louisiana State University Health Sciences Center, Shreveport, LA 71130, USA
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Roberts DJ, Strange PG. Mechanisms of inverse agonist action at D2 dopamine receptors. Br J Pharmacol 2005; 145:34-42. [PMID: 15735658 PMCID: PMC1576109 DOI: 10.1038/sj.bjp.0706073] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Mechanisms of inverse agonist action at the D2(short) dopamine receptor have been examined. Discrimination of G-protein-coupled and -uncoupled forms of the receptor by inverse agonists was examined in competition ligand-binding studies versus the agonist [3H]NPA at a concentration labelling both G-protein-coupled and -uncoupled receptors. Competition of inverse agonists versus [3H]NPA gave data that were fitted best by a two-binding site model in the absence of GTP but by a one-binding site model in the presence of GTP. K(i) values were derived from the competition data for binding of the inverse agonists to G-protein-uncoupled and -coupled receptors. K(coupled) and K(uncoupled) were statistically different for the set of compounds tested (ANOVA) but the individual values were different in a post hoc test only for (+)-butaclamol. These observations were supported by simulations of these competition experiments according to the extended ternary complex model. Inverse agonist efficacy of the ligands was assessed from their ability to reduce agonist-independent [35S]GTP gamma S binding to varying degrees in concentration-response curves. Inverse agonism by (+)-butaclamol and spiperone occurred at higher potency when GDP was added to assays, whereas the potency of (-)-sulpiride was unaffected. These data show that some inverse agonists ((+)-butaclamol, spiperone) achieve inverse agonism by stabilising the uncoupled form of the receptor at the expense of the coupled form. For other compounds tested, we were unable to define the mechanism.
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Affiliation(s)
- David J Roberts
- School of Animal and Microbial Sciences, University of Reading, Whiteknights, Reading RG6 6AJ
| | - Philip G Strange
- School of Animal and Microbial Sciences, University of Reading, Whiteknights, Reading RG6 6AJ
- Author for correspondence:
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Nickolls SA, Strange PG. The influence of G protein subtype on agonist action at D2 dopamine receptors. Neuropharmacology 2005; 47:860-72. [PMID: 15527820 DOI: 10.1016/j.neuropharm.2004.06.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2004] [Revised: 05/28/2004] [Accepted: 06/18/2004] [Indexed: 10/26/2022]
Abstract
In previous studies, we have shown that agonists influence the ability of D2 dopamine receptors to couple to G proteins and here we extend this work. The human D2Short dopamine receptor and a natural polymorphism of this D(2Short)(Ser311Cys), have been studied by co-expressing the receptors in insect cells with Gbeta1gamma2 and either Galpha(o), Galpha(i1), Galpha(i2) or Galpha(i3) G protein subunits. These preparations have been used to study the G protein coupling profiles of the two receptors and the influence of agonists. Receptor/G protein coupling was analysed in dopamine/[3H]spiperone competition binding experiments and through stimulation of [35S]GTPgammaS binding. Although the Ser311Cys polymorphism itself had no appreciable effect on the G protein coupling specificity of the D2 receptor, agonist stimulation of [35S]GTPgammaS binding, revealed that both dopamine and (+)-3PPP showed a clear preference for Galpha(o) compared to the Galpha(i) subtypes, but quinpirole did not. These results indicate that agonists are able to stabilise different receptor conformations with different abilities to couple to G proteins.
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Affiliation(s)
- Sarah A Nickolls
- School of Animal and Microbial Sciences, University of Reading, Whiteknights, Reading RG6 6AJ, UK
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45
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Millan MJ, Seguin L, Gobert A, Cussac D, Brocco M. The role of dopamine D3 compared with D2 receptors in the control of locomotor activity: a combined behavioural and neurochemical analysis with novel, selective antagonists in rats. Psychopharmacology (Berl) 2004; 174:341-57. [PMID: 14985929 DOI: 10.1007/s00213-003-1770-x] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2003] [Accepted: 12/04/2003] [Indexed: 11/30/2022]
Abstract
BACKGROUND The role of dopamine D(3)/D(2) receptors in the control of locomotion is poorly understood. OBJECTIVES To examine the influence of selective antagonists at D(3) or D(2) receptors on locomotion in rats, alone and in interaction with the preferential D(3) versus D(2) receptor agonist, PD128,907. METHODS Affinities of ligands at rat D(2) and cloned, human hD(3), hD(2S), hD(2L) and hD(4) sites were determined by standard procedures. Locomotion was monitored automatically in rats pre-habituated for 30 min to an open-field environment. Extracellular levels of dopamine (DA) were determined by dialysis in the nucleus accumbens and striatum. Drugs were given acutely via the systemic route. RESULTS PD128,907, which preferentially recognised D(3) versus D(2) sites, biphasically reduced and enhanced locomotion at "low" (0.01-0.63 mg/kg) and "high" (2.5-10 mg/kg) doses, respectively. L741,626 and S23199, which behaved as preferential D(2) versus D(3) receptor antagonists, enhanced the reduction in locomotion evoked by the low dose of PD128,907, blocked the increase provoked by the high dose and suppressed spontaneous locomotion alone. Analogous findings were obtained with haloperidol and raclopride which showed equilibrated affinity at D(2) and D(3) receptors. UH232 and AJ76, which showed a mild preference for D(3) versus D(2) sites, did not modify the effect of a low dose of PD128,907, slightly enhanced the hyperlocomotion elicited by the high dose and exerted little influence on locomotion alone. S14297 and U99194, which acted as preferential D(3) versus D(2) receptor antagonists, abolished the reduction in locomotion elicited by a low dose of PD128,907, potentiated the induction of locomotion by a high dose, and failed to influence locomotion alone. The actions of S14297 were stereoselective inasmuch as they were mimicked by the racemic form, S11566, but not by the inactive enantiomer, S17777. In contrast to S14297, S11566 and U99194, however, S33084, SB269,652, GR218,231 and N-[-4-['-(1-naphtyl)piperazine-1-yl]butyl] anthracene-2-carboxamide ("NGB-1"), highly selective D(3) versus D(2) receptor antagonists, were inactive under all conditions. PD128,907 (0.01-10.0 mg/kg) suppressed dialysate levels of DA in the nucleus accumbens and striatum, actions blocked by L741,626 and haloperidol, yet unaffected by S14297 and S33084. CONCLUSIONS The facilitatory influence of a "high" dose of PD128,907 upon locomotion is mediated by postsynaptic D(2) receptors and, possibly, countered by their D(3) counterparts. Correspondingly, selective blockade of D(2) but not of D(3) receptors alone suppresses motor function. The reduction in locomotion provoked by a "low" dose of PD128,907 may be mediated by D(2) autoreceptors, but a role of postsynaptic D(3) receptors cannot be excluded. Finally, mechanisms underlying the contrasting influence of chemically diverse D(3) receptor antagonists upon locomotion remain to be elucidated.
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Affiliation(s)
- Mark J Millan
- Psychopharmacology Department, Institut de Recherches Servier, Centre de Recherches de Croissy, 125 chemin de Ronde, 78290 Croissy/Seine, Paris, France.
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Akam E, Strange PG. Inverse agonist properties of atypical antipsychotic drugs. Biochem Pharmacol 2004; 67:2039-45. [PMID: 15135301 DOI: 10.1016/j.bcp.2004.02.017] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2003] [Accepted: 02/09/2004] [Indexed: 10/26/2022]
Abstract
Mechanisms of action of several atypical antipsychotic drugs have been examined at the D(2) dopamine receptor expressed in CHO cells. The drugs tested were found to exhibit inverse agonist activity at the D(2) dopamine receptor based on their effects to potentiate forskolin-stimulated cyclic AMP (cAMP) accumulation. Each of the antipsychotic drugs tested (clozapine, olanzapine, quetiapine and risperidone) increased cAMP accumulation to the same extent. The increase in cAMP was also similar to that seen with typical antipsychotic drugs. Inverse agonism at the D(2) dopamine receptor seems, therefore, to be a property common to all classes of antipsychotic drugs. The effect of sodium ions on the binding of the drugs to the receptor was also assessed. Each of the atypical antipsychotic drugs tested here bound with higher affinity in the absence of sodium ions. Previous studies have shown that some antipsychotic drugs are insensitive to sodium ions and some bind with higher affinity in the presence of sodium ions. Given that all of these antipsychotic drugs are inverse agonists, it may be concluded that this sodium ion sensitivity is unrelated to mechanisms of inverse agonism.
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Affiliation(s)
- Elizabeth Akam
- School of Animal and Microbial Sciences, University of Reading, Whiteknights, Reading RG66AJ, UK
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Roberts DJ, Lin H, Strange PG. Investigation of the mechanism of agonist and inverse agonist action at D2 dopamine receptors. Biochem Pharmacol 2004; 67:1657-65. [PMID: 15081865 DOI: 10.1016/j.bcp.2003.12.030] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2003] [Accepted: 12/17/2003] [Indexed: 11/17/2022]
Abstract
This study investigated, for the D2 dopamine receptor, the relation between the ability of agonists and inverse agonists to stabilise different states of the receptor and their relative efficacies. Ki values for agonists were determined in competition versus the binding of the antagonist [3H]spiperone. Competition data were fitted best by a two-binding site model (with the exception of bromocriptine, for which a one-binding site model provided the best fit) and agonist affinities for the higher (Kh) (G protein-coupled) and lower affinity (Kl) (G protein-uncoupled) sites determined. Ki values for agonists were also determined in competition versus the binding of the agonist [3H]N-propylnorapomorphine (NPA) to provide a second estimate of Kh. Maximal agonist effects (Emax) and their potencies (EC50) were determined from concentration-response curves for agonist stimulation of guanosine-5'-O-(3-[32S]thiotriphosphate) ([35S]GTPgammaS) binding. The ability of agonists to stabilise the G protein-coupled state of the receptor (Kl/Kh determined from ligand-binding assays) did not correlate with either of two measures of relative efficacy (relative Emax, Kl/EC50) of agonists determined in [35S]GTPgammaS-binding assays, when the data for all of the compounds tested were analysed. For a subset of compounds, however, there was a relation between Kl/Kh and Emax. Competition-binding data versus [3H]spiperone and [3H]NPA for a range of inverse agonists were fitted best by a one-binding site model. Ki values for the inverse agonists tested were slightly lower in competition versus [3H]NPA compared to [3H]spiperone. These data do not provide support for the idea that inverse agonists act by binding preferentially to the ground state of the receptor.
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Affiliation(s)
- David J Roberts
- School of Animal and Microbial Sciences, University of Reading, Whiteknights, Reading, RG6 6AJ, UK
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Maggio R, Scarselli M, Novi F, Millan MJ, Corsini GU. Potent activation of dopamine D3/D2 heterodimers by the antiparkinsonian agents, S32504, pramipexole and ropinirole. J Neurochem 2003; 87:631-41. [PMID: 14535946 DOI: 10.1046/j.1471-4159.2003.02038.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Recombinant, human dopamine D3 and D2 receptors form functional heterodimers upon co-expression in COS-7 cells. Herein, actions of the antiparkinsonian agents, S32504, ropinirole and pramipexole, at D3/D2L heterodimers were compared to their effects at the respective monomers and at split, chimeric D3trunk/D2tail and D2trunk/D3tail receptors: the trunk incorporated transmembrane domains (TDs) I-V and the tail TDs VI and VII. In binding assays with the antagonist [3H]nemonapride, all agonists were potent ligands of D3 receptors showing, respectively, 100-, 18- and 56-fold lower affinity at D2L receptors, mimicking the selective D3 receptor antagonist, S33084 (100-fold). At D3trunk/D2tail receptors, except for ropinirole, all drugs showed lower affinities than at D3 sites, whereas for D2trunk/D3tail receptors, affinities of all drugs were higher than at D2L sites. The proportion of high affinity binding sites recognized by S32504, pramipexole and ropinirole in membranes derived from cells co-expressing D3 and D2L sites was higher than in an equivalent mixture of membranes from cells expressing D3 or D2L sites, consistent with the promotion of heterodimer formation. In contrast, the percentage of high and low affinity sites (biphasic isotherms) recognized by S33084 was identical. Functional actions were determined by co-transfection of a chimeric adenylyl cyclase (AC)-V/VI insensitive to D3 receptors. Accordingly, D3 receptor-transfected cells were irresponsive whereas, in D2L receptor-transfected cells, agonists suppressed forskolin-stimulated cAMP production with modest potencies. In cells co-transfected with D3 and D2L receptors, S32504, ropinirole and pramipexole potently suppressed AC-V/VI with EC50s 33-, 19- and 11-fold lower than at D2L receptors, respectively. S32504 also suppressed AC-V/VI activity at split D3trunk/D2tail and D2trunk/D3tail chimeras transfected into COS-7 cells. In conclusion, antiparkinson agents behave as potent agonists at D3/D2'heterodimers', though any role in their actions in vivo remains to be demonstrated.
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Monczor F, Fernandez N, Legnazzi BL, Riveiro ME, Baldi A, Shayo C, Davio C. Tiotidine, a histamine H2 receptor inverse agonist that binds with high affinity to an inactive G-protein-coupled form of the receptor. Experimental support for the cubic ternary complex model. Mol Pharmacol 2003; 64:512-20. [PMID: 12869657 DOI: 10.1124/mol.64.2.512] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Knowing the importance for research and pharmacological uses of proper ligand classification into agonists, inverse agonists, and antagonists, the aim of this work was to study the behavior of tiotidine, a controversial histamine H2 receptor ligand. We found that tiotidine, described previously as an H2 antagonist, actually behaves as an inverse agonist in U-937 cells, diminishing basal cAMP levels. [3H]Tiotidine showed two binding sites, one with high affinity and low capacity and the other with low affinity and high capacity. The former site disappeared in the presence of guanosine 5'-O-(3-thio)triphosphate, indicating that it belongs to a subset of receptors coupled to G-protein, showing the classic binding profile for an agonist. Considering the occupancy models developed up to now, the only one that explains tiotidine dual behavior is the cubic ternary complex (CTC) model. This model allows G-protein to interact with the receptor even in the inactive state. We showed by theoretical simulations based on the CTC model of dose-response and binding experiments that tiotidine biases the system to a G-protein-coupled form of the receptor that is unable to evoke a response. This theoretical approach was supported by experimental results in which an unrelated G-protein-coupled receptor that also signals through Galphas-protein (beta2-adrenoreceptor) was impeded by tiotidine. This interference clearly implies that tiotidine biases the system to Galphas-coupled form of the H2 receptor and turns Galphas-protein less available to interact with beta2-adrenoreceptor. These findings not only show that tiotidine is an H2 inverse agonist in U-937 cells but also provide experimental support for the CTC model.
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Affiliation(s)
- Federico Monczor
- Laboratorio de Radioisótopos, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires. Junin 956 PB, 1113, Capital Federal, Argentina
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