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Song HY, Jung SW, Kim YS. Prokinetic Agents. THE KOREAN JOURNAL OF HELICOBACTER AND UPPER GASTROINTESTINAL RESEARCH 2022. [DOI: 10.7704/kjhugr.2022.0011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Gastrointestinal (GI) prokinetic agents are drugs that increase GI motility and promote the movement of contents in the GI tract by amplifying and controlling the contraction of GI smooth muscle. Currently used prokinetics increase GI motility by acting as a dopamine D<sub>2</sub> receptor antagonist (e.g., metoclopramide, domperidone, levosulpiride) and 5-HT<sub>4</sub> receptor agonist (e.g., mosapride, prucalopride). Some prokinetics also have a cholinesterase inhibitory property (e.g., itopride), and herb-derived prokinetics (e.g., motilitone) affect multiple receptors. Depending on the type and distribution of receptors on which the prokinetics bind, the effect(s) may be regional or throughout the GI tract. Most prokinetics have been used for functional dyspepsia and gastroparesis because they mainly affect upper GI motility. However, prucalopride, a highly selective 5-HT<sub>4</sub> receptor agonist, is used primarily to treat chronic constipation and pseudo-obstruction. Dopamine D<sub>2</sub> receptor antagonists also inhibit the D<sub>2</sub> receptor in the medulla oblongata chemoreceptor trigger zone; therefore, they can treat nausea and vomiting. However, short term use of dopamine D<sub>2</sub> antagonists at an appropriate dose is recommended because of their potential for central nervous system side effects by penetrating the blood-brain barrier. It is necessary to know the mechanism of action, each clinical trial’s characteristics, and the side effects of prokinetics to obtain the best clinical outcomes. This article aims to summarize the results of clinical studies related to the impact of currently available prokinetic agents in Korea on GI motility.
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Tosso RD, Zarycz MNC, Schiel A, Goicoechea Moro L, Baldoni HA, Angelina E, Enriz RD. Evaluating the conformational space of the active site of D 2 dopamine receptor. Scope and limitations of the standard docking methods. J Comput Chem 2022; 43:1298-1312. [PMID: 35638694 DOI: 10.1002/jcc.26938] [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: 01/03/2022] [Revised: 04/11/2022] [Accepted: 05/08/2022] [Indexed: 11/05/2022]
Abstract
We report here for the first time the potential energy surfaces (PES) of phenyletilamine (PEA) and meta-tyramine (m-OH-PEA) at the D2 dopamine receptor (D2DR) binding site. PESs not only allow us to observe all the critical points of the surface (minimums, maximums, and transition states), but also to note the ease or difficulty that each local minima have for their conformational inter-conversions and therefore know the conformational flexibility that these ligands have in their active sites. Taking advantage of possessing this valuable information, we analyze how accurate a standard docking study is in these cases. Our results indicate that although we have to be careful in how to carry out this type of study and to consider performing some extra-simulations, docking calculations can be satisfactory. In order to analyze in detail the different molecular interactions that are stabilizing the different ligand-receptor (L-R) complexes, we carried out quantum theory of atoms in molecules (QTAIM) computations and NMR shielding calculations. Although some of these techniques are a bit tedious and require more computational time, our results demonstrate the importance of performing computational simulations using different types of combined techniques (docking/MD/hybrid QM-MM/QTAIM and NMR shielding calculations) in order to obtain more accurate results. Our results allow us to understand in details the molecular interactions stabilizing and destabilizing the different L-R complexes reported here. Thus, the different activities observed for dopamine (DA), m-OH-PEA, and PEA can be clearly explained at molecular level.
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Affiliation(s)
- Rodrigo D Tosso
- Facultad de Química, Bioquímica y Farmacia, Universidad Nacional de San Luis, Instituto Multidisciplinario de Investigaciones Biológicas, San Luis, Argentina
| | - M Natalia C Zarycz
- Facultad de Química, Bioquímica y Farmacia, Universidad Nacional de San Luis, Instituto Multidisciplinario de Investigaciones Biológicas, San Luis, Argentina
| | - Ayelén Schiel
- Facultad de Química, Bioquímica y Farmacia, Universidad Nacional de San Luis, Instituto Multidisciplinario de Investigaciones Biológicas, San Luis, Argentina
| | - Luisa Goicoechea Moro
- Facultad de Química, Bioquímica y Farmacia, Universidad Nacional de San Luis, Instituto Multidisciplinario de Investigaciones Biológicas, San Luis, Argentina
| | - Héctor A Baldoni
- Facultad de Química, Bioquímica y Farmacia, Universidad Nacional de San Luis; Instituto de Matemáticas, San Luis, Argentina
| | - Emilio Angelina
- Laboratorio de Estructura Molecular y Propiedades, Facultad de Ciencias Exactas y Naturales y Agrimensura, Universidad Nacional del Nordeste, Instituto de Química Básica y Aplicada, Corrientes, Argentina
| | - Ricardo D Enriz
- Facultad de Química, Bioquímica y Farmacia, Universidad Nacional de San Luis, Instituto Multidisciplinario de Investigaciones Biológicas, San Luis, Argentina
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Ågren R, Sahlholm K. Evidence for Two Modes of Binding of the Negative Allosteric Modulator SB269,652 to the Dopamine D2 Receptor. Biomedicines 2021; 10:biomedicines10010022. [PMID: 35052702 PMCID: PMC8772941 DOI: 10.3390/biomedicines10010022] [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: 11/14/2021] [Revised: 12/21/2021] [Accepted: 12/21/2021] [Indexed: 11/16/2022] Open
Abstract
SB269,652 has been described as the first negative allosteric modulator (NAM) of the dopamine D2 receptor (D2R), however, the binding mode and allosteric mechanism of action of this ligand remain incompletely understood. SB269,652 comprises an orthosteric, primary pharmacophore and a secondary (or allosteric) pharmacophore joined by a hydrophilic cyclohexyl linker and is known to form corresponding interactions with the orthosteric binding site (OBS) and the secondary binding pocket (SBP) in the D2R. Here, we observed a surprisingly low potency of SB269,652 to negatively modulate the D2R-mediated activation of G protein-coupled inward-rectifier potassium channels (GIRK) and decided to perform a more detailed investigation of the interaction between dopamine and SB269,652. The results indicated that the SB269,652 inhibitory potency is increased 6.6-fold upon ligand pre-incubation, compared to the simultaneous co-application with dopamine. Mutagenesis experiments implicated both S193 in the OBS and E95 in the SBP in the effect of pre-application. The present findings extend previous knowledge about how SB269,652 competes with dopamine at the D2R and may be useful for the development of novel D2R ligands, such as antipsychotic drug candidates.
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Affiliation(s)
- Richard Ågren
- Department of Neuroscience, Karolinska Institutet, 17177 Stockholm, Sweden
- Correspondence: (R.Å.); (K.S.)
| | - Kristoffer Sahlholm
- Department of Neuroscience, Karolinska Institutet, 17177 Stockholm, Sweden
- Wallenberg Centre for Molecular Medicine, Department of Integrative Medical Biology, Umeå University, 90187 Umea, Sweden
- Correspondence: (R.Å.); (K.S.)
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Stepniewski TM, Mancini A, Ågren R, Torrens-Fontanals M, Semache M, Bouvier M, Sahlholm K, Breton B, Selent J. Mechanistic insights into dopaminergic and serotonergic neurotransmission - concerted interactions with helices 5 and 6 drive the functional outcome. Chem Sci 2021; 12:10990-11003. [PMID: 34522296 PMCID: PMC8386650 DOI: 10.1039/d1sc00749a] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2021] [Accepted: 06/15/2021] [Indexed: 01/14/2023] Open
Abstract
Brain functions rely on neurotransmitters that mediate communication between billions of neurons. Disruption of this communication can result in a plethora of psychiatric and neurological disorders. In this work, we combine molecular dynamics simulations, live-cell biosensor and electrophysiological assays to investigate the action of the neurotransmitter dopamine at the dopaminergic D2 receptor (D2R). The study of dopamine and closely related chemical probes reveals how neurotransmitter binding translates into the activation of distinct subsets of D2R effectors (i.e.: Gi2, GoB, Gz and β-arrestin 2). Ligand interactions with key residues in TM5 (S5.42) and TM6 (H6.55) in the D2R binding pocket yield a dopamine-like coupling signature, whereas exclusive TM5 interaction is typically linked to preferential G protein coupling (in particular GoB) over β-arrestin. Further experiments for serotonin receptors indicate that the reported molecular mechanism is shared by other monoaminergic neurotransmitter receptors. Ultimately, our study highlights how sequence variation in position 6.55 is used by nature to fine-tune β-arrestin recruitment and in turn receptor signaling and internalization of neurotransmitter receptors.
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Affiliation(s)
- Tomasz Maciej Stepniewski
- Research Programme on Biomedical Informatics (GRIB), Hospital del Mar Medical Research Institute (IMIM) - Pompeu Fabra University (UPF) Dr Aiguader 88 Barcelona E-08003 Spain
- InterAx Biotech AG, PARK InnovAARE 5234 Villigen Switzerland
| | - Arturo Mancini
- Domain Therapeutics NA Inc 7171 Frederick-Banting Saint-Laurent (QC) H4S 1Z9 Canada
| | - Richard Ågren
- Department of Neuroscience, Karolinska Institute Stockholm Sweden
| | - Mariona Torrens-Fontanals
- Research Programme on Biomedical Informatics (GRIB), Hospital del Mar Medical Research Institute (IMIM) - Pompeu Fabra University (UPF) Dr Aiguader 88 Barcelona E-08003 Spain
| | - Meriem Semache
- Domain Therapeutics NA Inc 7171 Frederick-Banting Saint-Laurent (QC) H4S 1Z9 Canada
| | - Michel Bouvier
- Department of Biochemistry and Molecular Medicine, Université de Montréal Montreal QC H3C 3J7 Canada
- Institute for Research in Immunology and Cancer (IRIC), Université de Montréal Montréal Québec H3T 1J4 Canada
| | - Kristoffer Sahlholm
- Department of Neuroscience, Karolinska Institute Stockholm Sweden
- Department of Integrative Medical Biology, Wallenberg Centre for Molecular Medicine, Umeå University 90187 Umeå Sweden
| | - Billy Breton
- Domain Therapeutics NA Inc 7171 Frederick-Banting Saint-Laurent (QC) H4S 1Z9 Canada
- Institute for Research in Immunology and Cancer (IRIC), Université de Montréal Montréal Québec H3T 1J4 Canada
| | - Jana Selent
- Research Programme on Biomedical Informatics (GRIB), Hospital del Mar Medical Research Institute (IMIM) - Pompeu Fabra University (UPF) Dr Aiguader 88 Barcelona E-08003 Spain
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Dopamine D 2 Receptor Agonist Binding Kinetics-Role of a Conserved Serine Residue. Int J Mol Sci 2021; 22:ijms22084078. [PMID: 33920848 PMCID: PMC8071183 DOI: 10.3390/ijms22084078] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 04/06/2021] [Accepted: 04/13/2021] [Indexed: 01/03/2023] Open
Abstract
The forward (kon) and reverse (koff) rate constants of drug–target interactions have important implications for therapeutic efficacy. Hence, time-resolved assays capable of measuring these binding rate constants may be informative to drug discovery efforts. Here, we used an ion channel activation assay to estimate the kons and koffs of four dopamine D2 receptor (D2R) agonists; dopamine (DA), p-tyramine, (R)- and (S)-5-OH-dipropylaminotetralin (DPAT). We further probed the role of the conserved serine S1935.42 by mutagenesis, taking advantage of the preferential interaction of (S)-, but not (R)-5-OH-DPAT with this residue. Results suggested similar koffs for the two 5-OH-DPAT enantiomers at wild-type (WT) D2R, both being slower than the koffs of DA and p-tyramine. Conversely, the kon of (S)-5-OH-DPAT was estimated to be higher than that of (R)-5-OH-DPAT, in agreement with the higher potency of the (S)-enantiomer. Furthermore, S1935.42A mutation lowered the kon of (S)-5-OH-DPAT and reduced the potency difference between the two 5-OH-DPAT enantiomers. Kinetic Kds derived from the koff and kon estimates correlated well with EC50 values for all four compounds across four orders of magnitude, strengthening the notion that our assay captured meaningful information about binding kinetics. The approach presented here may thus prove valuable for characterizing D2R agonist candidate drugs.
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Striatal dopaminergic alterations in Tourette's syndrome: a meta-analysis based on 16 PET and SPECT neuroimaging studies. Transl Psychiatry 2018; 8:143. [PMID: 30072700 PMCID: PMC6072751 DOI: 10.1038/s41398-018-0202-y] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Revised: 05/17/2018] [Accepted: 06/05/2018] [Indexed: 01/07/2023] Open
Abstract
Despite intense research, the underlying mechanisms and the etiology of Tourette's syndrome (TS) remain unknown. Data from molecular imaging studies targeting the dopamine system in Tourette patients are inconclusive. For a better understanding of the striatal dopamine function in adult dopamine-antagonist-free patients we performed a systematic review in August 2017 identifying 49 PET and SPECT studies on the topic of TS. A total of 8 studies appraised the dopamine transporter (DAT) with 111 Tourette patients and 93 healthy controls, and could be included in a meta-analytic approach. We found a significantly increased striatal DAT binding in Tourette patients (Hedges' g = 0.49; 95% CI: (0.01-0.98)), although this effect did not remain significant after correcting for age differences between cohorts. A second meta-analysis was performed for the striatal dopamine receptor including 8 studies with a total of 72 Tourette patients and 71 controls. This analysis revealed a nonsignificant trend toward lower dopamine 2/3 receptor binding in striatum of Tourette patients. Other analyses regarding study population characteristics in both the DAT and receptor meta-analysis did not show any meaningful results. Our results indicate that dopaminergic alterations in TS are likely and thereby this data would be in line with the current pathophysiological hypotheses of a dysfunction in the dopamine system, e.g., the hypothesis of tonic-phasic dysfunction. However, these analyses suffer from low effect sizes probably due to the heterogeneity of TS and highlight the need for further large-scaled neuroimaging studies.
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Amato D, Vernon AC, Papaleo F. Dopamine, the antipsychotic molecule: A perspective on mechanisms underlying antipsychotic response variability. Neurosci Biobehav Rev 2018; 85:146-159. [DOI: 10.1016/j.neubiorev.2017.09.027] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Revised: 09/20/2017] [Accepted: 09/26/2017] [Indexed: 12/12/2022]
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8
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Investigating the structural impact of S311C mutation in DRD2 receptor by molecular dynamics & docking studies. Biochimie 2016; 123:52-64. [DOI: 10.1016/j.biochi.2016.01.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 01/16/2016] [Indexed: 01/11/2023]
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9
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Kling RC, Clark T, Gmeiner P. Comparative MD Simulations Indicate a Dual Role for Arg1323.50 in Dopamine-Dependent D2R Activation. PLoS One 2016; 11:e0146612. [PMID: 26741139 PMCID: PMC4704829 DOI: 10.1371/journal.pone.0146612] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Accepted: 12/18/2015] [Indexed: 12/02/2022] Open
Abstract
Residue Arg3.50 belongs to the highly conserved DRY-motif of class A GPCRs, which is located at the bottom of TM3. On the one hand, Arg3.50 has been reported to help stabilize the inactive state of GPCRs, but on the other hand has also been shown to be crucial for stabilizing active receptor conformations and mediating receptor-G protein coupling. The combined results of these studies suggest that the exact function of Arg3.50 is likely to be receptor-dependent and must be characterized independently for every GPCR. Consequently, we now present comparative molecular-dynamics simulations that use our recently described inactive-state and Gα-bound active-state homology models of the dopamine D2 receptor (D2R), which are either bound to dopamine or ligand-free, performed to identify the function of Arg1323.50 in D2R. Our results are consistent with a dynamic model of D2R activation in which Arg1323.50 adopts a dual role, both by stabilizing the inactive-state receptor conformation and enhancing dopamine-dependent D2R-G protein coupling.
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Affiliation(s)
- Ralf C. Kling
- Department of Chemistry and Pharmacy, Emil Fischer Center, Friedrich Alexander University, Erlangen, Germany
- Department of Chemistry and Pharmacy, Computer Chemistry Center, Friedrich Alexander University, Erlangen, Germany
| | - Timothy Clark
- Department of Chemistry and Pharmacy, Computer Chemistry Center, Friedrich Alexander University, Erlangen, Germany
- Centre for Molecular Design, University of Portsmouth, King Henry Building, Portsmouth, United Kingdom
| | - Peter Gmeiner
- Department of Chemistry and Pharmacy, Emil Fischer Center, Friedrich Alexander University, Erlangen, Germany
- * E-mail:
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Weichert D, Banerjee A, Hiller C, Kling RC, Hübner H, Gmeiner P. Molecular Determinants of Biased Agonism at the Dopamine D2 Receptor. J Med Chem 2015; 58:2703-17. [DOI: 10.1021/jm501889t] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Dietmar Weichert
- Department of Chemistry and
Pharmacy, Medicinal Chemistry, Emil Fischer Center, Friedrich Alexander University, Schuhstraße 19, 91052 Erlangen, Germany
| | - Ashutosh Banerjee
- Department of Chemistry and
Pharmacy, Medicinal Chemistry, Emil Fischer Center, Friedrich Alexander University, Schuhstraße 19, 91052 Erlangen, Germany
| | - Christine Hiller
- Department of Chemistry and
Pharmacy, Medicinal Chemistry, Emil Fischer Center, Friedrich Alexander University, Schuhstraße 19, 91052 Erlangen, Germany
| | - Ralf C. Kling
- Department of Chemistry and
Pharmacy, Medicinal Chemistry, Emil Fischer Center, Friedrich Alexander University, Schuhstraße 19, 91052 Erlangen, Germany
| | - Harald Hübner
- Department of Chemistry and
Pharmacy, Medicinal Chemistry, Emil Fischer Center, Friedrich Alexander University, Schuhstraße 19, 91052 Erlangen, Germany
| | - Peter Gmeiner
- Department of Chemistry and
Pharmacy, Medicinal Chemistry, Emil Fischer Center, Friedrich Alexander University, Schuhstraße 19, 91052 Erlangen, Germany
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Salmas RE, Yurtsever M, Stein M, Durdagi S. Modeling and protein engineering studies of active and inactive states of human dopamine D2 receptor (D2R) and investigation of drug/receptor interactions. Mol Divers 2015; 19:321-32. [DOI: 10.1007/s11030-015-9569-3] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2014] [Accepted: 01/11/2015] [Indexed: 01/11/2023]
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12
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Kling RC, Tschammer N, Lanig H, Clark T, Gmeiner P. Active-state model of a dopamine D2 receptor-Gαi complex stabilized by aripiprazole-type partial agonists. PLoS One 2014; 9:e100069. [PMID: 24932547 PMCID: PMC4059746 DOI: 10.1371/journal.pone.0100069] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Accepted: 05/20/2014] [Indexed: 11/18/2022] Open
Abstract
Partial agonists exhibit a submaximal capacity to enhance the coupling of one receptor to an intracellular binding partner. Although a multitude of studies have reported different ligand-specific conformations for a given receptor, little is known about the mechanism by which different receptor conformations are connected to the capacity to activate the coupling to G-proteins. We have now performed molecular-dynamics simulations employing our recently described active-state homology model of the dopamine D2 receptor-Gαi protein-complex coupled to the partial agonists aripiprazole and FAUC350, in order to understand the structural determinants of partial agonism better. We have compared our findings with our model of the D2R-Gαi-complex in the presence of the full agonist dopamine. The two partial agonists are capable of inducing different conformations of important structural motifs, including the extracellular loop regions, the binding pocket and, in particular, intracellular G-protein-binding domains. As G-protein-coupling to certain intracellular epitopes of the receptor is considered the key step of allosterically triggered nucleotide-exchange, it is tempting to assume that impaired coupling between the receptor and the G-protein caused by distinct ligand-specific conformations is a major determinant of partial agonist efficacy.
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Affiliation(s)
- Ralf C. Kling
- Department of Chemistry and Pharmacy, Emil Fischer Center, Friedrich Alexander University, Erlangen, Germany
- Department of Chemistry and Pharmacy, Computer Chemistry Center, Friedrich Alexander University, Erlangen, Germany
| | - Nuska Tschammer
- Department of Chemistry and Pharmacy, Emil Fischer Center, Friedrich Alexander University, Erlangen, Germany
| | - Harald Lanig
- Department of Chemistry and Pharmacy, Computer Chemistry Center, Friedrich Alexander University, Erlangen, Germany
- Central Institute for Scientific Computing, Friedrich Alexander University, Erlangen, Germany
| | - Timothy Clark
- Department of Chemistry and Pharmacy, Computer Chemistry Center, Friedrich Alexander University, Erlangen, Germany
- Centre for Molecular Design, University of Portsmouth, King Henry Building, Portsmouth, United Kingdom
| | - Peter Gmeiner
- Department of Chemistry and Pharmacy, Emil Fischer Center, Friedrich Alexander University, Erlangen, Germany
- * E-mail:
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Kling RC, Lanig H, Clark T, Gmeiner P. Active-state models of ternary GPCR complexes: determinants of selective receptor-G-protein coupling. PLoS One 2013; 8:e67244. [PMID: 23826246 PMCID: PMC3691126 DOI: 10.1371/journal.pone.0067244] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Accepted: 05/16/2013] [Indexed: 11/29/2022] Open
Abstract
Based on the recently described crystal structure of the β2 adrenergic receptor - Gs-protein complex, we report the first molecular-dynamics simulations of ternary GPCR complexes designed to identify the selectivity determinants for receptor-G-protein binding. Long-term molecular dynamics simulations of agonist-bound β2AR-Gαs and D2R-Gαi complexes embedded in a hydrated bilayer environment and computational alanine-scanning mutagenesis identified distinct residues of the N-terminal region of intracellular loop 3 to be crucial for coupling selectivity. Within the G-protein, specific amino acids of the α5-helix, the C-terminus of the Gα-subunit and the regions around αN-β1 and α4-β6 were found to determine receptor recognition. Knowledge of these determinants of receptor-G-protein binding selectivity is essential for designing drugs that target specific receptor/G-protein combinations.
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MESH Headings
- Alanine/genetics
- Amino Acid Sequence
- Binding Sites
- Dopamine/metabolism
- GTP-Binding Protein alpha Subunits, Gi-Go/chemistry
- GTP-Binding Protein alpha Subunits, Gi-Go/metabolism
- GTP-Binding Proteins/metabolism
- Histidine/metabolism
- Ligands
- Models, Biological
- Molecular Dynamics Simulation
- Molecular Sequence Data
- Multiprotein Complexes/metabolism
- Mutagenesis
- Protein Structure, Secondary
- Receptors, Adrenergic, beta-2/chemistry
- Receptors, Adrenergic, beta-2/metabolism
- Receptors, Dopamine/chemistry
- Receptors, Dopamine/metabolism
- Receptors, G-Protein-Coupled/chemistry
- Receptors, G-Protein-Coupled/metabolism
- Sequence Alignment
- Structural Homology, Protein
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Affiliation(s)
- Ralf C. Kling
- Department of Chemistry and Pharmacy, Emil Fischer Center, Friedrich Alexander University, Erlangen, Germany
- Department of Chemistry and Pharmacy, Computer Chemistry Center, Friedrich Alexander University, Erlangen, Germany
| | - Harald Lanig
- Department of Chemistry and Pharmacy, Computer Chemistry Center, Friedrich Alexander University, Erlangen, Germany
| | - Timothy Clark
- Department of Chemistry and Pharmacy, Computer Chemistry Center, Friedrich Alexander University, Erlangen, Germany
- Centre for Molecular Design, University of Portsmouth, King Henry Building, Portsmouth, United Kingdom
| | - Peter Gmeiner
- Department of Chemistry and Pharmacy, Emil Fischer Center, Friedrich Alexander University, Erlangen, Germany
- * E-mail:
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14
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Malo M, Persson R, Svensson P, Luthman K, Brive L. Development of 7TM receptor-ligand complex models using ligand-biased, semi-empirical helix-bundle repacking in torsion space: application to the agonist interaction of the human dopamine D2 receptor. J Comput Aided Mol Des 2013; 27:277-91. [PMID: 23553533 PMCID: PMC3639355 DOI: 10.1007/s10822-013-9640-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2012] [Accepted: 03/20/2013] [Indexed: 11/30/2022]
Abstract
Prediction of 3D structures of membrane proteins, and of G-protein coupled receptors (GPCRs) in particular, is motivated by their importance in biological systems and the difficulties associated with experimental structure determination. In the present study, a novel method for the prediction of 3D structures of the membrane-embedded region of helical membrane proteins is presented. A large pool of candidate models are produced by repacking of the helices of a homology model using Monte Carlo sampling in torsion space, followed by ranking based on their geometric and ligand-binding properties. The trajectory is directed by weak initial restraints to orient helices towards the original model to improve computation efficiency, and by a ligand to guide the receptor towards a chosen conformational state. The method was validated by construction of the β1 adrenergic receptor model in complex with (S)-cyanopindolol using bovine rhodopsin as template. In addition, models of the dopamine D2 receptor were produced with the selective and rigid agonist (R)-N-propylapomorphine ((R)-NPA) present. A second quality assessment was implemented by evaluating the results from docking of a library of 29 ligands with known activity, which further discriminated between receptor models. Agonist binding and recognition by the dopamine D2 receptor is interpreted using the 3D structure model resulting from the approach. This method has a potential for modeling of all types of helical transmembrane proteins for which a structural template with sequence homology sufficient for homology modeling is not available or is in an incorrect conformational state, but for which sufficient empirical information is accessible.
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Affiliation(s)
- Marcus Malo
- Department of Chemistry and Molecular Biology, University of Gothenburg, SE-412 96 Göteborg, Sweden
| | - Ronnie Persson
- Department of Chemistry and Molecular Biology, University of Gothenburg, SE-412 96 Göteborg, Sweden
| | - Peder Svensson
- NeuroSearch Sweden AB, Arvid Wallgrens Backe 20, SE-413 46 Göteborg, Sweden
- Present Address: Astra Zeneca R&D Mölndal, SE-431 83 Mölndal, Sweden
| | - Kristina Luthman
- Department of Chemistry and Molecular Biology, University of Gothenburg, SE-412 96 Göteborg, Sweden
| | - Lars Brive
- Department of Chemistry and Molecular Biology, University of Gothenburg, SE-412 96 Göteborg, Sweden
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Box 440, SE-405 30 Göteborg, Sweden
- Cygnal Bioscience, Björnvägen 15, SE-435 43 Pixbo, Sweden
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15
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Malo M, Brive L, Luthman K, Svensson P. Investigation of D₂ receptor-agonist interactions using a combination of pharmacophore and receptor homology modeling. ChemMedChem 2012; 7:471-82, 338. [PMID: 22315215 PMCID: PMC3382189 DOI: 10.1002/cmdc.201100545] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2011] [Revised: 01/05/2012] [Indexed: 01/21/2023]
Abstract
A combined modeling approach was used to identify structural factors that underlie the structure–activity relationships (SARs) of full dopamine D2 receptor agonists and structurally similar inactive compounds. A 3D structural model of the dopamine D2 receptor was constructed, with the agonist (−)-(R)-2-OH-NPA present in the binding site during the modeling procedure. The 3D model was evaluated and compared with our previously published D2 agonist pharmacophore model. The comparison revealed an inconsistency between the projected hydrogen bonding feature (Ser-TM5) in the pharmacophore model and the TM5 region in the structure model. A new refined pharmacophore model was developed, guided by the shape of the binding site in the receptor model and with less emphasis on TM5 interactions. The combination of receptor and pharmacophore modeling also identified the importance of His3936.55 for agonist binding. This convergent 3D pharmacophore and protein structure modeling strategy is considered to be general and can be highly useful in less well-characterized systems to explore ligand–receptor interactions. The strategy has the potential to identify weaknesses in the individual models and thereby provides an opportunity to improve the discriminating predictivity of both pharmacophore searches and structure-based virtual screens.
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Affiliation(s)
- Marcus Malo
- Department of Chemistry, Medicinal Chemistry, University of Gothenburg, 41296 Göteborg, Sweden
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16
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Sahlholm K, Barchad-Avitzur O, Marcellino D, Gómez-Soler M, Fuxe K, Ciruela F, Arhem P. Agonist-specific voltage sensitivity at the dopamine D2S receptor--molecular determinants and relevance to therapeutic ligands. Neuropharmacology 2011; 61:937-49. [PMID: 21752340 DOI: 10.1016/j.neuropharm.2011.06.022] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2011] [Revised: 05/20/2011] [Accepted: 06/24/2011] [Indexed: 10/18/2022]
Abstract
Voltage sensitivity has been demonstrated for some GPCRs. At the dopamine D(2S) receptor, this voltage sensitivity is agonist-specific; some agonists, including dopamine, exhibit decreased potency at depolarized potentials, whereas others are not significantly affected. In the present study, we examined some of the receptor-agonist interactions contributing to these differences, and investigated how dopamine D(2S) receptor voltage sensitivity affects clinically used dopamine agonists. GIRK channel activation in voltage-clamped Xenopus oocytes was used as readout of receptor activation. Structurally distinct agonists and complementary site-directed mutagenesis of the receptor's binding site were used to investigate the role of agonist-receptor interactions. We also confirmed that the depolarization-induced decrease of dopamine potency in GIRK activation is correlated by decreased binding of radiolabeled dopamine, and by decreased potency in G protein activation. In the mutagenesis experiments, a conserved serine residue as well as the conserved aspartate in the receptor's binding site were found to be important for voltage sensitive potency of dopamine. Furthermore, the voltage sensitivity of the receptor had distinct effects on different therapeutic D(2) agonists. Depolarization decreased the potency of several compounds, whereas for others, efficacy was reduced. For some agonists, both potency and efficacy were diminished, whereas for others still, neither parameter was significantly altered. The present work identifies some of the ligand-receptor interactions which determine agonist-specific effects of voltage at the dopamine D(2S) receptor. The observed differences between therapeutic agonists might be clinically relevant, and make them potential tools for investigating the roles of dopamine D(2) receptor voltage sensitivity in native tissue.
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Ortore G, Tuccinardi T, Orlandini E, Martinelli A. Different Binding Modes of Structurally Diverse Ligands for Human D3DAR. J Chem Inf Model 2010; 50:2162-75. [DOI: 10.1021/ci100290f] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Gabriella Ortore
- Dipartimento di Scienze Farmaceutiche, Università di Pisa, via Bonanno 6, 56126 Pisa, Italy
| | - Tiziano Tuccinardi
- Dipartimento di Scienze Farmaceutiche, Università di Pisa, via Bonanno 6, 56126 Pisa, Italy
| | - Elisabetta Orlandini
- Dipartimento di Scienze Farmaceutiche, Università di Pisa, via Bonanno 6, 56126 Pisa, Italy
| | - Adriano Martinelli
- Dipartimento di Scienze Farmaceutiche, Università di Pisa, via Bonanno 6, 56126 Pisa, Italy
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18
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Malo M, Brive L, Luthman K, Svensson P. Selective pharmacophore models of dopamine D(1) and D(2) full agonists based on extended pharmacophore features. ChemMedChem 2010; 5:232-46. [PMID: 20077461 DOI: 10.1002/cmdc.200900398] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
This study is focused on the identification of structural features that determine the selectivity of dopamine receptor agonists toward D(1) and D(2) receptors. Selective pharmacophore models were developed for both receptors. The models were built by using projected pharmacophoric features that represent the main agonist interaction sites in the receptor (the Ser residues in TM5 and the Asp in TM3), a directional aromatic feature in the ligand, a feature with large positional tolerance representing the positively charged nitrogen in the ligand, and sets of excluded volumes reflecting the shapes of the receptors. The sets of D(1) and D(2) ligands used for modeling were carefully selected from published sources and consist of structurally diverse, conformationally rigid full agonists as active ligands together with structurally related inactives. The robustness of the models in discriminating actives from inactives was tested against four ensembles of conformations generated by using different established methods and different force fields. The reasons for the selectivity can be attributed to both geometrical differences in the arrangement of the features, e.g., different tilt angels of the pi system, as well as shape differences covered by the different sets of excluded volumes. This work provides useful information for the design of new D(1) and D(2) agonists and also for comparative homology modeling of D(1) and D(2) receptors. The approach is general and could therefore be applied to other ligand-protein interactions for which no experimental protein structure is available.
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Affiliation(s)
- Marcus Malo
- Department of Chemistry, Medicinal Chemistry, University of Gothenburg, 41296 Göteborg, Sweden
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19
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McRobb FM, Capuano B, Crosby IT, Chalmers DK, Yuriev E. Homology Modeling and Docking Evaluation of Aminergic G Protein-Coupled Receptors. J Chem Inf Model 2010; 50:626-37. [DOI: 10.1021/ci900444q] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- Fiona M. McRobb
- Medicinal Chemistry and Drug Action, Monash Institute of Pharmaceutical Sciences, Monash University (Parkville Campus), 381 Royal Parade, Parkville, VIC 3052 Australia
| | - Ben Capuano
- Medicinal Chemistry and Drug Action, Monash Institute of Pharmaceutical Sciences, Monash University (Parkville Campus), 381 Royal Parade, Parkville, VIC 3052 Australia
| | - Ian T. Crosby
- Medicinal Chemistry and Drug Action, Monash Institute of Pharmaceutical Sciences, Monash University (Parkville Campus), 381 Royal Parade, Parkville, VIC 3052 Australia
| | - David K. Chalmers
- Medicinal Chemistry and Drug Action, Monash Institute of Pharmaceutical Sciences, Monash University (Parkville Campus), 381 Royal Parade, Parkville, VIC 3052 Australia
| | - Elizabeth Yuriev
- Medicinal Chemistry and Drug Action, Monash Institute of Pharmaceutical Sciences, Monash University (Parkville Campus), 381 Royal Parade, Parkville, VIC 3052 Australia
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20
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Tschammer N, Dörfler M, Hübner H, Gmeiner P. Engineering a GPCR-ligand pair that simulates the activation of D(2L) by Dopamine. ACS Chem Neurosci 2010; 1:25-35. [PMID: 22778805 DOI: 10.1021/cn900001b] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2009] [Accepted: 09/03/2009] [Indexed: 02/05/2023] Open
Abstract
In the past decade, engineered G-protein-coupled receptors activated solely by synthetic ligands (RASSLs) have been implemented as a new means to study neurotransmission, which is controlled by G-protein-coupled receptors in vitro and in vivo. In this study, we report an engineered dopamine receptor D(2L) F390(6.52)W, which is the first identified RASSL for the dopamine receptor family. The mutant receptor is characterized by a disrupted ligand binding and complete loss of efficacy for the endogenous ligand, dopamine, which is putatively due to a sterically induced perturbation of H-bonding with conserved serine residues in TM5. Based on this model, we rationally developed an aminoindane-derived set of agonists. Because these agonists forgo analogous H-bonding functionalities, their binding energy does not depend on the respective interactions. Binding affinity and potency were optimized by ligand modifications bearing molecular appendages that obviously interact with a secondary recognition site provided by four hydrophobic residues in TM2 and TM3. Thus, the ferrocenyl carboxamide 5b (FAUC 185) was identified as a synthetic agonist that is able to stimulate the mutant receptor in a manner similar to that by which endogenous dopamine activates the D(2L) wild-type receptor. The engineered dopamine receptor D(2L) F390(6.52)W in combination with FAUC 185 (5b) provides a new tool to probe GPCR functions selectively in specific cell populations in vitro and in vivo.
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Affiliation(s)
- Nuska Tschammer
- Department of Chemistry and Pharmacy, Emil Fischer Center, Friedrich Alexander University, Schuhstrasse 19, D-91052 Erlangen, Germany
| | - Miriam Dörfler
- Department of Chemistry and Pharmacy, Emil Fischer Center, Friedrich Alexander University, Schuhstrasse 19, D-91052 Erlangen, Germany
| | - Harald Hübner
- Department of Chemistry and Pharmacy, Emil Fischer Center, Friedrich Alexander University, Schuhstrasse 19, D-91052 Erlangen, Germany
| | - Peter Gmeiner
- Department of Chemistry and Pharmacy, Emil Fischer Center, Friedrich Alexander University, Schuhstrasse 19, D-91052 Erlangen, Germany
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21
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Sipos A, Mueller FKU, Lehmann J, Berényi S, Antus S. Synthesis and Pharmacological Evaluation of Thiazole and Isothiazole Derived Apomorphines. Arch Pharm (Weinheim) 2009; 342:557-68. [DOI: 10.1002/ardp.200900100] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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22
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Katritch V, Reynolds KA, Cherezov V, Hanson MA, Roth CB, Yeager M, Abagyan R. Analysis of full and partial agonists binding to beta2-adrenergic receptor suggests a role of transmembrane helix V in agonist-specific conformational changes. J Mol Recognit 2009; 22:307-18. [PMID: 19353579 DOI: 10.1002/jmr.949] [Citation(s) in RCA: 105] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The 2.4 A crystal structure of the beta(2)-adrenergic receptor (beta(2)AR) in complex with the high-affinity inverse agonist (-)-carazolol provides a detailed structural framework for the analysis of ligand recognition by adrenergic receptors. Insights into agonist binding and the corresponding conformational changes triggering G-protein coupled receptor (GPCR) activation mechanism are of special interest. Here we show that while the carazolol pocket captured in the beta(2)AR crystal structure accommodates (-)-isoproterenol and other agonists without steric clashes, a finite movement of the flexible extracellular part of TM-V helix (TM-Ve) obtained by receptor optimization in the presence of docked ligand can further improve the calculated binding affinities for agonist compounds. Tilting of TM-Ve towards the receptor axis provides a more complete description of polar receptor-ligand interactions for full and partial agonists, by enabling optimal engagement of agonists with two experimentally identified anchor sites, formed by Asp113/Asn312 and Ser203/Ser204/Ser207 side chains. Further, receptor models incorporating a flexible TM-V backbone allow reliable prediction of binding affinities for a set of diverse ligands, suggesting potential utility of this approach to design of effective and subtype-specific agonists for adrenergic receptors. Systematic differences in capacity of partial, full and inverse agonists to induce TM-V helix tilt in the beta(2)AR model suggest potential role of TM-V as a conformational "rheostat" involved in the whole spectrum of beta(2)AR responses to small molecule signals.
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Affiliation(s)
- Vsevolod Katritch
- Department of Molecular Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.
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23
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Sahlholm K, Marcellino D, Nilsson J, Fuxe K, Arhem P. Voltage-sensitivity at the human dopamine D2S receptor is agonist-specific. Biochem Biophys Res Commun 2008; 377:1216-21. [PMID: 18983826 DOI: 10.1016/j.bbrc.2008.10.117] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2008] [Accepted: 10/26/2008] [Indexed: 01/23/2023]
Abstract
Recently, we and others have shown that agonist potencies at some, but not all, G protein-coupled receptors are voltage-sensitive. Several of those studies employed electrophysiology assays in Xenopus oocytes with G protein-coupled potassium channels as a readout. Using this assay, we have now obtained evidence that voltage-sensitivity at the dopamine D(2S) receptor is agonist-specific. Whereas the potency of dopamine at the D(2S) receptor is decreased by depolarization, the potencies of beta-phenethylamine, p- and m-tyramine are voltage-insensitive. Furthermore, both monohydroxylated and non-hydroxylated N,N-dipropyl-2-aminotetralin compounds are voltage-sensitive. Differential activation of G protein subtypes or differential ratios between effector and active G protein do not underlie this agonist-selective voltage-sensitivity. This is the first demonstration of voltage-sensitive and voltage-insensitive behaviour of different agonists acting via the same receptor.
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Affiliation(s)
- Kristoffer Sahlholm
- Department of Neuroscience, Karolinska Institutet, SE-171 77 Stockholm, Sweden
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24
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de Graaf C, Foata N, Engkvist O, Rognan D. Molecular modeling of the second extracellular loop of G-protein coupled receptors and its implication on structure-based virtual screening. Proteins 2008; 71:599-620. [PMID: 17972285 DOI: 10.1002/prot.21724] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The current study describes the validation of high-throughput modeling procedures for the construction of the second extracellular loop (ecl2) of all nonolfactory human G Protein-coupled receptors. Our modeling flowchart is based on the alignment of essential residues determining the particular ecl2 fold observed in the bovine rhodopsin (bRho) crystal structure. For a set of GPCR targets, the dopamine D2 receptor (DRD2), adenosine A3 receptor (AA3R), and the thromboxane A2 receptor (TA2R), the implications of including ecl2 atomic coordinates is evaluated in terms of structure-based virtual screening accuracy: the suitability of the 3D models to distinguish between known antagonists and randomly chosen decoys using automated docking approaches. The virtual screening results of different models describing increasingly exhaustive receptor representations (seven helices only, seven helices and ecl2 loop, full model) have been compared. Explicit modeling of the ecl2 loop was found to be important in only one of three test cases whereas a loopless model was shown to be accurate enough in the two other receptors. An exhaustive comparison of ecl2 loops of 365 receptors to that of bRho suggests that explicit ecl2 loop modeling should be reserved to receptors where loop building can be guided by experimental restraints.
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Affiliation(s)
- Chris de Graaf
- Bioinformatics of the Drug, CNRS UMR 7175-LC1, Université Louis Pasteur Strasbourg I, Illkirch F-67401, France
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25
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Al-Fulaij MA, Ren Y, Beinborn M, Kopin AS. Identification of amino acid determinants of dopamine 2 receptor synthetic agonist function. J Pharmacol Exp Ther 2007; 321:298-307. [PMID: 17204745 DOI: 10.1124/jpet.106.116384] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The human dopamine 2 receptor (hD2R) modulates locomotor activity, hormone secretion, and neuropsychiatric function. Current knowledge of the hD2R structure is in large part derived from mutagenesis studies and molecular pharmacologic analysis together with homology modeling using bovine rhodopsin as a template. In this study, we utilized comparison of the Drosophila D2-like receptor (DD2R) with the hD2R as a novel approach for identifying candidate amino acids that are determinants of ligand potency and/or efficacy. We focused our studies on four dopaminergic ligands that are used in the treatment of Parkinson's disease: bromocriptine, pergolide, piribedil, and ropinirole. All four ligands are potent agonists at the wild-type hD2R, whereas only bromocriptine shows comparable function at the DD2R. We performed site-directed mutagenesis to replace hD2R amino acids (modeled to project into the ligand binding pocket) with corresponding fly residues, and vice versa. Substitution of three amino acids in the hD2R with the homologous DD2R residues (V91A, C118S, and L170I) led to a pronounced loss of pergolide potency and efficacy. A converse triple amino acid substitution of human residues into the fly receptor (DD2R-A133V/S160C/I211L) markedly enhanced pergolide efficacy and potency at the mutant DD2R. The same substitutions also converted piribedil and ropinirole, which lacked appreciable activity on the DD2R, to partial agonists. These findings show the important role of these three residues in drug-receptor interactions. Our study illustrates that comparison of a mammalian receptor with an invertebrate homolog complements previously described strategies for defining G protein-coupled receptor structure-function relationships.
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Affiliation(s)
- Munya A Al-Fulaij
- Program in Genetics, Sackler School of Graduate Biomedical Sciences, Tufts University School of Medicine, Boston, Massachusetts, USA
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26
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Floresca CZ, Schetz JA. Dopamine receptor microdomains involved in molecular recognition and the regulation of drug affinity and function. J Recept Signal Transduct Res 2005; 24:207-39. [PMID: 15521362 DOI: 10.1081/rrs-200032088] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
A cationic protonatable amine moiety on dopaminergic ligands forms a high affinity reinforced ionic bond with an anionic aspartic acid at position 3.32 of dopamine receptors. When present, catechol hydroxyls of the ligands form hydrogen bonds with serines at position 5.42, 5.43, and 5.46, and this network of hydrogen bonds serves to orient ligands in the binding-site crevice and increase their binding affinity. A steric clash between aromatic moieties of the ligands and aromatic amino acids of the receptor (e.g., H6.55, F6.52 or F6.51 and W6.48) is likely to be propagated in domino-like fashion along the length of TM6, which is believed to trigger activation of the receptor. Specifically, it is the change in the conformation of W6.48 from an orientation perpendicular to the plane of the lipid membrane to one that is parallel that is believed to result in activation. Molecular determinants that mediate the D4/D2-selectivity of many extremely D4-selective 1,4-DAP ligands, include a nonconserved cluster of bulky amino acids at the TM2/TM3 interface (positions 2.61, 3.28 and 3.29).
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Affiliation(s)
- Christina Z Floresca
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, Texas 76107-2699, USA
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27
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Tonini M, Cipollina L, Poluzzi E, Crema F, Corazza GR, De Ponti F. Review article: clinical implications of enteric and central D2 receptor blockade by antidopaminergic gastrointestinal prokinetics. Aliment Pharmacol Ther 2004; 19:379-90. [PMID: 14871277 DOI: 10.1111/j.1365-2036.2004.01867.x] [Citation(s) in RCA: 186] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Antidopaminergic gastrointestinal prokinetics (bromopride, clebopride, domperidone, levosulpiride and metoclopramide) have been exploited clinically for the management of motor disorders of the upper gastrointestinal tract, including functional dyspepsia, gastric stasis of various origins and emesis. The prokinetic effect of these drugs is mediated through the blockade of enteric (neuronal and muscular) inhibitory D2 receptors. The pharmacological profiles of the marketed compounds differ in terms of their molecular structure, affinity at D2 receptors, ability to interact with other receptor systems [5-hydroxytryptamine-3 (5-HT3) and 5-HT4 receptors for metoclopramide; 5-HT4 receptors for levosulpiride) and ability to permeate the blood-brain barrier (compared with the other compounds, domperidone does not easily cross the barrier). It has been suggested that the serotonergic (5-HT4) component of some antidopaminergic prokinetics may enhance their therapeutic efficacy in gastrointestinal disorders, such as functional dyspepsia and diabetic gastroparesis. The antagonism of central D2 receptors may lead to both therapeutic (e.g. anti-emetic effect due to D2 receptor blockade in the area postrema) and adverse (including hyperprolactinaemia and extrapyramidal dystonic reactions) effects. As the pituitary (as well as the area postrema) is outside the blood-brain barrier, hyperprolactinaemia is a side-effect occurring with all antidopaminergic prokinetics, although to different extents. Extrapyramidal reactions are most commonly observed with compounds crossing the blood-brain barrier, although with some differences amongst the various agents. Prokinetics with a high dissociation constant compared with that of dopamine at the D2 receptor (i.e. compounds that bind loosely to D2 receptors in the nigrostriatal pathway) elicit fewer extrapyramidal signs and symptoms. A knowledge of central and peripheral D2 receptor pharmacology can help the clinician to choose between the antidopaminergic prokinetics to obtain a more favourable risk/benefit ratio.
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Affiliation(s)
- M Tonini
- Department of Physiological and Pharmacological Sciences, University of Pavia, Pavia, Italy.
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28
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Alder JT, Hacksell U, Strange PG. Analysis of molecular determinants of affinity and relative efficacy of a series of R- and S-2-(dipropylamino)tetralins at the 5-HT1A serotonin receptor. Br J Pharmacol 2003; 138:1129-39. [PMID: 12684269 PMCID: PMC1573746 DOI: 10.1038/sj.bjp.0705085] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
1. Factors influencing agonist affinity and relative efficacy have been studied for the 5-HT(1A) serotonin receptor using membranes of CHO cells expressing the human form of the receptor and a series of R-and S-2-(dipropylamino)tetralins (nonhydroxylated and monohydroxylated (5-OH, 6-OH, 7-OH, 8-OH) species). 2. Ligand binding studies were used to determine dissociation constants for agonist binding to the 5-HT(1A) receptor: (a) K(i) values for agonists were determined in competition versus the binding of the agonist [(3)H]-8-OH DPAT. Competition data were all fitted best by a one-binding site model. (b) K(i) values for agonists were also determined in competition versus the binding of the antagonist [(3)H]-NAD-199. Competition data were all fitted best by a two-binding site model, and agonist affinities for the higher (K(h)) and lower affinity (K(l)) sites were determined. 3. The ability of the agonists to activate the 5-HT(1A) receptor was determined using stimulation of [(35)S]-GTPgammaS binding. Maximal effects of agonists (E(max)) and their potencies (EC(50)) were determined from concentration/response curves for stimulation of [(35)S]-GTPgammaS binding. 4. K(l)/K(h) determined from ligand binding assays correlated with the relative efficacy (relative E(max)) of agonists determined in [(35)S]-GTPgammaS binding assays. There was also a correlation between K(l)/K(h) and K(l)/EC(50) for agonists determined from ligand binding and [(35)S]-GTPgammaS binding assays. 5. Simulations of agonist binding and effect data were performed using the Ternary Complex Model in order to assess the use of K(l)/K(h) for predicting the relative efficacy of agonists.
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Affiliation(s)
- J Tracy Alder
- School of Animal and Microbial Sciences, University of Reading, Whiteknights, Reading, Berkshire RG6 6AJ U.K
| | - Uli Hacksell
- ACADIA Pharmaceuticals, 3911 Sorrento Valley Boulevard, San Diego, CA 92121, U.S.A
| | - Philip G Strange
- School of Animal and Microbial Sciences, University of Reading, Whiteknights, Reading, Berkshire RG6 6AJ U.K
- Author for correspondence:
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29
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Payne SL, Johansson AM, Strange PG. Mechanisms of ligand binding and efficacy at the human D2(short) dopamine receptor. J Neurochem 2002; 82:1106-17. [PMID: 12358758 DOI: 10.1046/j.1471-4159.2002.01046.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Mechanisms of ligand binding and receptor activation for the human D2(short) dopamine receptor have been probed using two homologous series of monohydroxylated and dihydroxylated agonists (phenylethylamines and 2-dipropylaminotetralins). In ligand binding studies, the majority of compounds exhibited competition curves versus [3H]spiperone that were best fitted using a two site binding model. The compounds had different abilities (potencies and maximal effects) to stimulate [35S]GTPgammaS binding and to inhibit forskolin-stimulated cAMP accumulation. From the data it can be concluded that: (i) the ability of an agonist to stabilize receptor/G protein coupling can be used to predict agonist efficacy for some groups of compounds (2-dipropylaminotetralins) but not for others (phenylethylamines); (ii) the receptor may be activated by unhydroxylated compounds; (iii) single hydroxyl groups or pairs of hydroxyl groups on the agonist may contribute to binding affinity, potency and efficacy; and (iv) for the 2-dipropylaminotetralin series two modes of agonist/receptor interaction have been identified associated with different relative efficacy.
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Affiliation(s)
- Sarah L Payne
- School of Animal and Microbial Sciences, University of Reading, UK
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