1
|
Kirchhofer SB, Lim VJY, Ernst S, Karsai N, Ruland JG, Canals M, Kolb P, Bünemann M. Differential interaction patterns of opioid analgesics with µ opioid receptors correlate with ligand-specific voltage sensitivity. eLife 2023; 12:e91291. [PMID: 37983079 PMCID: PMC10849675 DOI: 10.7554/elife.91291] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Accepted: 11/19/2023] [Indexed: 11/21/2023] Open
Abstract
The µ opioid receptor (MOR) is the key target for analgesia, but the application of opioids is accompanied by several issues. There is a wide range of opioid analgesics, differing in their chemical structure and their properties of receptor activation and subsequent effects. A better understanding of ligand-receptor interactions and the resulting effects is important. Here, we calculated the respective binding poses for several opioids and analyzed interaction fingerprints between ligand and receptor. We further corroborated the interactions experimentally by cellular assays. As MOR was observed to display ligand-induced modulation of activity due to changes in membrane potential, we further analyzed the effects of voltage sensitivity on this receptor. Combining in silico and in vitro approaches, we defined discriminating interaction patterns responsible for ligand-specific voltage sensitivity and present new insights into their specific effects on activation of the MOR.
Collapse
Affiliation(s)
- Sina B Kirchhofer
- Department of Pharmacology and Clinical Pharmacy, University of MarburgMarburgGermany
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, Queen's Medical Centre, University of NottinghamNottinghamUnited Kingdom
- Centre of Membrane Protein and Receptors, Universities of Birmingham and NottinghamMidlandsUnited Kingdom
| | - Victor Jun Yu Lim
- Department of Pharmaceutical Chemistry, University of MarburgMarburgGermany
| | - Sebastian Ernst
- Department of Pharmacology and Clinical Pharmacy, University of MarburgMarburgGermany
| | - Noemi Karsai
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, Queen's Medical Centre, University of NottinghamNottinghamUnited Kingdom
- Centre of Membrane Protein and Receptors, Universities of Birmingham and NottinghamMidlandsUnited Kingdom
| | - Julia G Ruland
- Department of Pharmacology and Clinical Pharmacy, University of MarburgMarburgGermany
| | - Meritxell Canals
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, Queen's Medical Centre, University of NottinghamNottinghamUnited Kingdom
- Centre of Membrane Protein and Receptors, Universities of Birmingham and NottinghamMidlandsUnited Kingdom
| | - Peter Kolb
- Department of Pharmaceutical Chemistry, University of MarburgMarburgGermany
| | - Moritz Bünemann
- Department of Pharmacology and Clinical Pharmacy, University of MarburgMarburgGermany
| |
Collapse
|
2
|
Xie B, Goldberg A, Shi L. A comprehensive evaluation of the potential binding poses of fentanyl and its analogs at the µ-opioid receptor. Comput Struct Biotechnol J 2022; 20:2309-2321. [PMID: 35615021 PMCID: PMC9123087 DOI: 10.1016/j.csbj.2022.05.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2022] [Revised: 05/05/2022] [Accepted: 05/06/2022] [Indexed: 11/30/2022] Open
Abstract
Fentanyl and its analogs are selective agonists of the µ-opioid receptor (MOR). Among novel synthetic opioids (NSOs), they dominate the recreational drug market and are the main culprits for the opioid crisis, which has been exacerbated by the COVID-19 pandemic. By taking advantage of the crystal structures of the MOR, several groups have investigated the binding mechanism of fentanyl, but have not reached a consensus, in terms of both the binding orientation and the fentanyl conformation. Thus, the binding mechanism of fentanyl at the MOR remains an unsolved and challenging question. Here, we carried out a systematic computational study to investigate the preferred fentanyl conformations, and how these conformations are being accommodated in the MOR binding pocket. We characterized the free energy landscape of fentanyl conformations with metadynamics simulations, and compared and evaluated several possible fentanyl binding conditions in the MOR with long-timescale molecular dynamics simulations. Our results indicate that the most preferred binding pose in the MOR binding pocket corresponds well with the global minimum on the energy landscape of fentanyl in the absence of the receptor, while the energy landscape can be reconfigured by modifying the fentanyl scaffold. The interactions with the receptor may stabilize a slightly unfavored fentanyl conformation in an alternative binding pose. By extending similar investigations to fentanyl analogs, our findings establish a structure–activity relationship of fentanyl binding at the MOR. In addition to providing a structural basis to understand the potential toxicity of the emerging NSOs, such insights will contribute to developing new, safer analgesics.
Collapse
|
3
|
Opioid Receptors and Protonation-Coupled Binding of Opioid Drugs. Int J Mol Sci 2021; 22:ijms222413353. [PMID: 34948150 PMCID: PMC8707250 DOI: 10.3390/ijms222413353] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2021] [Revised: 12/09/2021] [Accepted: 12/09/2021] [Indexed: 01/01/2023] Open
Abstract
Opioid receptors are G-protein-coupled receptors (GPCRs) part of cell signaling paths of direct interest to treat pain. Pain may associate with inflamed tissue characterized by acidic pH. The potentially low pH at tissue targeted by opioid drugs in pain management could impact drug binding to the opioid receptor, because opioid drugs typically have a protonated amino group that contributes to receptor binding, and the functioning of GPCRs may involve protonation change. In this review, we discuss the relationship between structure, function, and dynamics of opioid receptors from the perspective of the usefulness of computational studies to evaluate protonation-coupled opioid-receptor interactions.
Collapse
|
4
|
Ricarte A, Dalton JAR, Giraldo J. Structural Assessment of Agonist Efficacy in the μ-Opioid Receptor: Morphine and Fentanyl Elicit Different Activation Patterns. J Chem Inf Model 2021; 61:1251-1274. [PMID: 33448226 DOI: 10.1021/acs.jcim.0c00890] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Over the past two decades, the opioid epidemic in the United States and Canada has evidenced the need for a better understanding of the molecular mechanisms of medications used to fight pain. Morphine and fentanyl are widely used in opiate-mediated analgesia for the treatment of chronic pain. These compounds target the μ-opioid receptor (MOR), a class A G protein-coupled receptor (GPCR). In light of described higher efficacy of fentanyl with respect to morphine, we have performed independent μs-length unbiased molecular dynamics (MD) simulations of MOR complexes with each of these ligands, including the MOR antagonist naltrexone as a negative control. Consequently, MD simulations totaling 58 μs have been conducted to elucidate at the atomic level ligand-specific receptor activity and signal transmission in the MOR. In particular, we have identified stable binding poses of morphine and fentanyl, which interact differently with the MOR. Different ligand-receptor interaction landscapes directly induce sidechain conformational changes of orthosteric pocket residues: Asp1493.32, Tyr1503.33, Gln1262.60, and Lys2355.39. The induced conformations determine Asp1493.32-Tyr3287.43 sidechain-sidechain interactions and Trp2956.48-Ala2425.46 sidechain-backbone H-bond formations, as well as Met1533.36 conformational changes. In addition to differences in ligand binding, different intracellular receptor conformational changes are observed as morphine preferentially activates transmembrane (TM) helices: TM3 and TM5, while fentanyl preferentially activates TM6 and TM7. As conformational changes in TM6 and TM7 are widely described as being the most crucial aspect in GPCR activation, this may contribute to the greater efficacy of fentanyl over morphine. These computationally observed functional differences between fentanyl and morphine may provide new avenues for the design of safer but not weaker opioid drugs because it is desirable to increase the safety of medicines without sacrificing their efficacy.
Collapse
Affiliation(s)
- Adrián Ricarte
- Laboratory of Molecular Neuropharmacology and Bioinformatics, Unitat de Bioestadística and Institut de Neurociències, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain.,Unitat de Neurociència Traslacional, Parc Taulí Hospital Universitari, Institut d'Investigació i Innovació Parc Taulí (I3PT), Institut de Neurociències, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain.,Instituto de Salud Carlos III, Centro de Investigación Biomédica en Red de Salud Mental, CIBERSAM, 28029 Madrid, Spain
| | - James A R Dalton
- Laboratory of Molecular Neuropharmacology and Bioinformatics, Unitat de Bioestadística and Institut de Neurociències, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain.,Unitat de Neurociència Traslacional, Parc Taulí Hospital Universitari, Institut d'Investigació i Innovació Parc Taulí (I3PT), Institut de Neurociències, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain.,Instituto de Salud Carlos III, Centro de Investigación Biomédica en Red de Salud Mental, CIBERSAM, 28029 Madrid, Spain
| | - Jesús Giraldo
- Laboratory of Molecular Neuropharmacology and Bioinformatics, Unitat de Bioestadística and Institut de Neurociències, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain.,Unitat de Neurociència Traslacional, Parc Taulí Hospital Universitari, Institut d'Investigació i Innovació Parc Taulí (I3PT), Institut de Neurociències, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain.,Instituto de Salud Carlos III, Centro de Investigación Biomédica en Red de Salud Mental, CIBERSAM, 28029 Madrid, Spain
| |
Collapse
|
5
|
Molecular insights into the interaction of hemorphin and its targets. Sci Rep 2019; 9:14747. [PMID: 31611567 PMCID: PMC6791854 DOI: 10.1038/s41598-019-50619-w] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Accepted: 09/17/2019] [Indexed: 12/20/2022] Open
Abstract
Hemorphins are atypical endogenous opioid peptides produced by the cleavage of hemoglobin beta chain. Several studies have reported the therapeutic potential of hemorphin in memory enhancement, blood regulation, and analgesia. However, the mode of interaction of hemorphin with its target remains largely elusive. The decapeptide LVV-hemorphin-7 is the most stable form of hemorphin. It binds with high affinity to mu-opioid receptors (MOR), angiotensin-converting enzyme (ACE) and insulin-regulated aminopeptidase (IRAP). In this study, computational methods were used extensively to elucidate the most likely binding pose of mammalian LVV-hemorphin-7 with the aforementioned proteins and to calculate the binding affinity. Additionally, alignment of mammalian hemorphin sequences showed that the hemorphin sequence of the camel harbors a variation - a Q > R substitution at position 8. This study also investigated the binding affinity and the interaction mechanism of camel LVV-hemorphin-7 with these proteins. To gain a better understanding of the dynamics of the molecular interactions between the selected targets and hemorphin peptides, 100 ns molecular dynamics simulations of the best-ranked poses were performed. Simulations highlighted major interactions between the peptides and key residues in the binding site of the proteins. Interestingly, camel hemorphin had a higher binding affinity and showed more interactions with all three proteins when compared to the canonical mammalian LVV-hemorphin-7. Thus, camel LVV-hemorphin-7 could be explored as a potent therapeutic agent for memory loss, hypertension, and analgesia.
Collapse
|
6
|
Binding mode analyses of NAP derivatives as mu opioid receptor selective ligands through docking studies and molecular dynamics simulation. Bioorg Med Chem 2017; 25:2463-2471. [PMID: 28302509 DOI: 10.1016/j.bmc.2017.03.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Revised: 02/27/2017] [Accepted: 03/03/2017] [Indexed: 01/02/2023]
Abstract
Mu opioid receptor selective antagonists are highly desirable because of their utility as pharmacological probes for receptor characterization and functional studies. Furthermore, the mu opioid receptors act as an important target in drug abuse and addiction treatment. Previously, we reported NAP as a novel lead compound with high selectivity and affinity towards the mu opioid receptor. Based on NAP, we have synthesized its derivatives and further characterized their binding affinities and selectivity towards the receptor. NMP and NGP were identified as the two most selective MOR ligands among NAP derivatives. In the present study, molecular modeling methods were applied to assess the dual binding modes of NAP derivatives, particularly on NMP and NGP, in three opioid receptors, in order to analyze the effects of structural modifications on the pyridyl ring of NAP on the binding affinity and selectivity. The results indicated that the steric hindrance, electrostatic, and hydrophobic effects caused by the substituents on the pyridyl ring of NAP contributed complimentarily on the binding affinity and selectivity of NAP derivatives to three opioid receptors. Analyses of these contributions provided insights on future design of more potent and selective mu opioid receptor ligands.
Collapse
|
7
|
Vardy E, Sassano MF, Rennekamp AJ, Kroeze WK, Mosier PD, Westkaemper RB, Stevens CW, Katritch V, Stevens RC, Peterson RT, Roth BL. Single Amino Acid Variation Underlies Species-Specific Sensitivity to Amphibian Skin-Derived Opioid-like Peptides. ACTA ACUST UNITED AC 2016; 22:764-75. [PMID: 26091169 DOI: 10.1016/j.chembiol.2015.05.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Revised: 04/14/2015] [Accepted: 05/01/2015] [Indexed: 01/08/2023]
Abstract
It has been suggested that the evolution of vertebrate opioid receptors (ORs) follow a vector of increased functionality. Here, we test this idea by comparing human and frog ORs. Interestingly, some of the most potent opioid peptides known have been isolated from amphibian skin secretions. Here we show that such peptides (dermorphin and deltorphin) are highly potent in the human receptors and inactive in frog ORs. The molecular basis for the insensitivity of the frog ORs to these peptides was studied using chimeras and molecular modeling. The insensitivity of the delta OR (DOR) to deltorphin was due to variation of a single amino acid, Trp7.35, which is a leucine in mammalian DORs. Notably, Trp7.35 is completely conserved in all known DOR sequences from lamprey, fish, and amphibians. The deltorphin-insensitive phenotype was verified in fish. Our results provide a molecular explanation for the species selectivity of skin-derived opioid peptides.
Collapse
Affiliation(s)
- Eyal Vardy
- Department of Pharmacology, UNC Chapel Hill Medical School, 4072 Genetic Medicine Building, 120 Mason Farm Road, Chapel Hill, NC 27514, USA
| | - Maria F Sassano
- Department of Pharmacology, UNC Chapel Hill Medical School, 4072 Genetic Medicine Building, 120 Mason Farm Road, Chapel Hill, NC 27514, USA
| | - Andrew J Rennekamp
- Cardiovascular Research Center and Division of Cardiology, Department of Medicine, Massachusetts General Hospital, Harvard Medical School, 149 13(th) Street, Charlestown, MA 02129, USA; Broad Institute, 7 Cambridge Center, Cambridge, MA 02142, USA
| | - Wesley K Kroeze
- Department of Pharmacology, UNC Chapel Hill Medical School, 4072 Genetic Medicine Building, 120 Mason Farm Road, Chapel Hill, NC 27514, USA
| | - Philip D Mosier
- Department of Medicinal Chemistry, Virginia Commonwealth University School of Pharmacy, Richmond, VA 23298, USA
| | - Richard B Westkaemper
- Department of Medicinal Chemistry, Virginia Commonwealth University School of Pharmacy, Richmond, VA 23298, USA
| | - Craig W Stevens
- Department of Pharmacology & Physiology, Oklahoma State University Center for Health Sciences, 1111 West 17(th) Street, Tulsa, OK 74107, USA
| | - Vsevolod Katritch
- Department of Biological Sciences and Chemistry, Bridge Institute, University of Southern California, Los Angeles, CA 90089, USA
| | - Raymond C Stevens
- Department of Biological Sciences and Chemistry, Bridge Institute, University of Southern California, Los Angeles, CA 90089, USA
| | - Randall T Peterson
- Cardiovascular Research Center and Division of Cardiology, Department of Medicine, Massachusetts General Hospital, Harvard Medical School, 149 13(th) Street, Charlestown, MA 02129, USA; Broad Institute, 7 Cambridge Center, Cambridge, MA 02142, USA
| | - Bryan L Roth
- Department of Pharmacology, UNC Chapel Hill Medical School, 4072 Genetic Medicine Building, 120 Mason Farm Road, Chapel Hill, NC 27514, USA.
| |
Collapse
|
8
|
Kaserer T, Lantero A, Schmidhammer H, Spetea M, Schuster D. μ Opioid receptor: novel antagonists and structural modeling. Sci Rep 2016; 6:21548. [PMID: 26888328 PMCID: PMC4757823 DOI: 10.1038/srep21548] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Accepted: 01/27/2016] [Indexed: 11/08/2022] Open
Abstract
The μ opioid receptor (MOR) is a prominent member of the G protein-coupled receptor family and the molecular target of morphine and other opioid drugs. Despite the long tradition of MOR-targeting drugs, still little is known about the ligand-receptor interactions and structure-function relationships underlying the distinct biological effects upon receptor activation or inhibition. With the resolved crystal structure of the β-funaltrexamine-MOR complex, we aimed at the discovery of novel agonists and antagonists using virtual screening tools, i.e. docking, pharmacophore- and shape-based modeling. We suggest important molecular interactions, which active molecules share and distinguish agonists and antagonists. These results allowed for the generation of theoretically validated in silico workflows that were employed for prospective virtual screening. Out of 18 virtual hits evaluated in in vitro pharmacological assays, three displayed antagonist activity and the most active compound significantly inhibited morphine-induced antinociception. The new identified chemotypes hold promise for further development into neurochemical tools for studying the MOR or as potential therapeutic lead candidates.
Collapse
Affiliation(s)
- Teresa Kaserer
- Computer-Aided Molecular Design Group, Department of Pharmaceutical Chemistry, Institute of Pharmacy and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
| | - Aquilino Lantero
- Opioid Research Group, Department of Pharmaceutical Chemistry, Institute of Pharmacy and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
| | - Helmut Schmidhammer
- Opioid Research Group, Department of Pharmaceutical Chemistry, Institute of Pharmacy and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
| | - Mariana Spetea
- Opioid Research Group, Department of Pharmaceutical Chemistry, Institute of Pharmacy and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
| | - Daniela Schuster
- Computer-Aided Molecular Design Group, Department of Pharmaceutical Chemistry, Institute of Pharmacy and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
| |
Collapse
|
9
|
Abstract
Opiates are among the oldest medications available to manage a number of medical problems. Although pain is the current focus, early use initially focused upon the treatment of dysentery. Opium contains high concentrations of both morphine and codeine, along with thebaine, which is used in the synthesis of a number of semisynthetic opioid analgesics. Thus, it is not surprising that new agents were initially based upon the morphine scaffold. The concept of multiple opioid receptors was first suggested almost 50 years ago (Martin, 1967), opening the possibility of new classes of drugs, but the morphine-like agents have remained the mainstay in the medical management of pain. Termed mu, our understanding of these morphine-like agents and their receptors has undergone an evolution in thinking over the past 35 years. Early pharmacological studies identified three major classes of receptors, helped by the discovery of endogenous opioid peptides and receptor subtypes-primarily through the synthesis of novel agents. These chemical biologic approaches were then eclipsed by the molecular biology revolution, which now reveals a complexity of the morphine-like agents and their receptors that had not been previously appreciated.
Collapse
Affiliation(s)
- Gavril W Pasternak
- Memorial Sloan-Kettering Cancer Center, 1275 York Ave, New York, NY 10065.
| | | |
Collapse
|
10
|
Binding mode characterization of 6α- and 6β-N-heterocyclic substituted naltrexamine derivatives via docking in opioid receptor crystal structures and site-directed mutagenesis studies: application of the 'message-address' concept in development of mu opioid receptor selective antagonists. Bioorg Med Chem 2013; 21:6405-13. [PMID: 24055076 DOI: 10.1016/j.bmc.2013.08.042] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2013] [Revised: 08/15/2013] [Accepted: 08/23/2013] [Indexed: 01/20/2023]
Abstract
Highly selective opioid receptor antagonists are essential pharmacological probes in opioid receptor structural characterization and opioid agonist functional studies. Currently, there is no highly selective, nonpeptidyl and reversible mu opioid receptor antagonist available. Among a series of naltrexamine derivatives that have been designed and synthesized, two compounds, NAP and NAQ, were previously identified as novel leads for this purpose based on their in vitro and in vivo pharmacological profiles. Both compounds displayed high binding affinity and selectivity to the mu opioid receptor. To further study the interaction of these two ligands with the three opioid receptors, the recently released opioid receptor crystal structures were employed in docking studies to further test our original hypothesis that the ligands recognize a unique 'address' domain in the mu opioid receptor involving Trp318 that facilitates their selectivity. These modeling results were supported by site-directed mutagenesis studies on the mu opioid receptor, where the mutants Y210A and W318A confirmed the role of the latter in binding. Such work not only enriched the 'message-address' concept, also facilitated our next generation ligand design and development.
Collapse
|
11
|
Marcu J, Shore DM, Kapur A, Trznadel M, Makriyannis A, Reggio PH, Abood ME. Novel insights into CB1 cannabinoid receptor signaling: a key interaction identified between the extracellular-3 loop and transmembrane helix 2. J Pharmacol Exp Ther 2013; 345:189-97. [PMID: 23426954 DOI: 10.1124/jpet.112.201046] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Activation of the cannabinoid CB1 receptor (CB1) is modulated by aspartate residue D2.63(176) in transmembrane helix (TMH) 2. Interestingly, D2.63 does not affect the affinity for ligand binding at the CB1 receptor. Studies in class A G protein-coupled receptors have suggested an ionic interaction between residues of TMH2 and 7. In this report, modeling studies identified residue K373 in the extracellular-3 (EC-3) loop in charged interactions with D2.63. We investigated this possibility by performing reciprocal mutations and biochemical studies. D2.63(176)A, K373A, D2.63(176)A-K373A, and the reciprocal mutant with the interacting residues juxtaposed D2.63(176)K-K373D were characterized using radioligand binding and guanosine 5'-3-O-(thio)triphosphate functional assays. None of the mutations resulted in a significant change in the binding affinity of N-(piperidiny-1-yl)-5-(4-chlorophenyl)-1-(2,4-dichloro-phenyl)-4-methyl-1H-pyrazole-3-carboxamide hydrochloride (SR141716A) or (-)-3cis -[2-hydroxyl-4-(1,1-dimethyl-heptyl)phenyl]-trans-4-[3-hydroxyl-propyl] cyclohexan-1-ol (CP55,940). Modeling studies indicated that binding-site interactions and energies of interaction for CP55,940 were similar between wild-type and mutant receptors. However, the signaling of CP55,940, and (R)-(+)-[2,3-dihydro-5-methyl-3-[(4-morpholinyl)methyl]-pyrrolo[1,2,3-de]-1,4-benzoxazin-6-yl](1-naphthalenyl)-methanone mesylate (WIN55,212-2) was impaired at the D2.63(176)A-K373A and the single-alanine mutants. In contrast, the reciprocal D2.63(176)K-K373D mutant regained function for both CP55,940 and WIN55,212-2. Computational results indicate that the D2.63(176)-K373 ionic interaction strongly influences the conformation(s) of the EC-3 loop, providing a structure-based rationale for the importance of the EC-3 loop to signal transduction in CB1. The putative ionic interaction results in the EC-3 loop pulling over the top (extracellular side) of the receptor; this EC-3 loop conformation may serve protective and mechanistic roles. These results suggest that the ionic interaction between D2.63(176) and K373 is important for CB1 signal transduction.
Collapse
Affiliation(s)
- Jahan Marcu
- Department of Anatomy and Cell Biology, Center for Substance Abuse Research, Temple University, Philadelphia, PA 19140, USA
| | | | | | | | | | | | | |
Collapse
|
12
|
Cui X, Yeliseev A, Liu R. Ligand interaction, binding site and G protein activation of the mu opioid receptor. Eur J Pharmacol 2013; 702:309-15. [PMID: 23415745 DOI: 10.1016/j.ejphar.2013.01.060] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2012] [Revised: 01/24/2013] [Accepted: 01/31/2013] [Indexed: 10/27/2022]
Abstract
With the recently solved crystal structure of the murine mu opioid receptor, the elucidation of the structure function relationships of the human mu receptor becomes feasible. In this study, we analyzed the available structural information along with ligand binding and G protein activation of human mu receptor. Affinity determinations were performed in a HEK293 cell line stably transfected with the human mu opioid receptor for 6 different agonists (morphine, DMAGO, and herkinorn) and antagonists (naloxone, beta-Funaltrexamine, and Norbinaltorphimine). G protein activation was investigated in membrane preparations containing human mu receptors treated with the agonist, partial agonist, or antagonist compounds. 4DKL.pdb was utilized for structural analysis and docking calculations for 28 mu receptor ligands. The predicted affinities from docking were compared with those experimentally determined. While all known ligands bind to the receptor through the same binding site that is large enough to accommodate molecules of various sizes, interaction with D147 (D149 in human mu receptor) is essential for binding. No distinguishable interaction pattern in the binding site for agonist, partial agonist, or antagonist to predict pharmacological activities was found. The failure to reconcile the predicted affinities from docking with experimental values indicates that the receptor might undergo significant conformational changes from one state to the other states upon different ligand binding. A simplified model to understand the complicated system is proposed and further study on these multiple conformations using high resolution structural approaches is suggested.
Collapse
Affiliation(s)
- Xu Cui
- Department of Anesthesiology, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | | | | |
Collapse
|
13
|
De Wachter R, de Graaf C, Keresztes A, Vandormael B, Ballet S, Tóth G, Rognan D, Tourwé D. Synthesis, Biological Evaluation, and Automated Docking of Constrained Analogues of the Opioid Peptide H-Dmt-d-Ala-Phe-Gly-NH2 Using the 4- or 5-Methyl Substituted 4-Amino-1,2,4,5-tetrahydro-2-benzazepin-3-one Scaffold. J Med Chem 2011; 54:6538-47. [DOI: 10.1021/jm2003574] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Rien De Wachter
- Department of Organic Chemistry, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium
| | - Chris de Graaf
- Structural Chemogenomics, UMR 7200 CNRS-UdS, Université de Strasbourg, Illkirch F-67401, France
- Leiden/Amsterdam Center for Drug Research, Division of Medicinal Chemistry, Faculty of Science, VU University Amsterdam, Amsterdam, The Netherlands
| | - Atilla Keresztes
- Institute of Biochemistry, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary
| | - Bart Vandormael
- Department of Organic Chemistry, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium
| | - Steven Ballet
- Department of Organic Chemistry, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium
| | - Géza Tóth
- Institute of Biochemistry, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary
| | - Didier Rognan
- Structural Chemogenomics, UMR 7200 CNRS-UdS, Université de Strasbourg, Illkirch F-67401, France
| | - Dirk Tourwé
- Department of Organic Chemistry, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium
| |
Collapse
|
14
|
Ślusarz MJ. Molecular modeling study of the opioid receptor interactions with series of cyclic deltorphin analogues. J Pept Sci 2011; 17:554-64. [DOI: 10.1002/psc.1371] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2010] [Revised: 02/18/2011] [Accepted: 02/21/2011] [Indexed: 11/08/2022]
|
15
|
Li G, Aschenbach LCK, He H, Selley DE, Zhang Y. 14-O-Heterocyclic-substituted naltrexone derivatives as non-peptide mu opioid receptor selective antagonists: design, synthesis, and biological studies. Bioorg Med Chem Lett 2009; 19:1825-9. [PMID: 19217280 PMCID: PMC2802822 DOI: 10.1016/j.bmcl.2008.12.093] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2008] [Revised: 12/19/2008] [Accepted: 12/19/2008] [Indexed: 11/26/2022]
Abstract
Mu opioid receptor antagonists have clinical utility and are important research tools. To develop non-peptide and highly selective mu opioid receptor antagonist, a series of 14-O-heterocyclic-substituted naltrexone derivatives were designed, synthesized, and evaluated. These compounds showed subnanomolar-to-nanomolar binding affinity for the mu opioid receptor. Among them, compound 1 exhibited the highest selectivity for the mu opioid receptor over the delta and kappa receptors. These results implicated an alternative 'address' domain in the extracellular loops of the mu opioid receptor.
Collapse
Affiliation(s)
- Guo Li
- Department of Medicinal Chemistry, Virginia Commonwealth University, 410 North 12th Street, PO Box 980613, Richmond, VA 23298-0613, USA
| | - Lindsey C. K. Aschenbach
- Department of Medicinal Chemistry, Virginia Commonwealth University, 410 North 12th Street, PO Box 980613, Richmond, VA 23298-0613, USA
| | - Hengjun He
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, 410 North 12th Street, PO Box 980613, Richmond, VA 23298-0613, USA
| | - Dana E. Selley
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, 410 North 12th Street, PO Box 980613, Richmond, VA 23298-0613, USA
| | - Yan Zhang
- Department of Medicinal Chemistry, Virginia Commonwealth University, 410 North 12th Street, PO Box 980613, Richmond, VA 23298-0613, USA
| |
Collapse
|
16
|
Li G, Aschenbach LC, Chen J, Cassidy MP, Stevens DL, Gabra BH, Selley DE, Dewey WL, Westkaemper RB, Zhang Y. Design, synthesis, and biological evaluation of 6alpha- and 6beta-N-heterocyclic substituted naltrexamine derivatives as mu opioid receptor selective antagonists. J Med Chem 2009; 52:1416-27. [PMID: 19199782 PMCID: PMC2880636 DOI: 10.1021/jm801272c] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Opioid receptor selective antagonists are important pharmacological probes in opioid receptor structural characterization and opioid agonist functional study. Thus far, a nonpeptidyl, highly selective and reversible mu opioid receptor (MOR) antagonist is unavailable. On the basis of our modeling studies, a series of novel naltrexamine derivatives have been designed and synthesized. Among them, two compounds were identified as leads based on the results of in vitro and in vivo assays. Both of them displayed high binding affinity for the MOR (K(i) = 0.37 and 0.55 nM). Compound 6 (NAP) showed over 700-fold selectivity for the MOR over the delta receptor (DOR) and more than 150-fold selectivity over the kappa receptor (KOR). Compound 9 (NAQ) showed over 200-fold selectivity for the MOR over the DOR and approximately 50-fold selectivity over the KOR. Thus these two novel ligands will serve as leads to further develop more potent and selective antagonists for the MOR.
Collapse
MESH Headings
- Amino Acid Sequence
- Analgesics/chemical synthesis
- Analgesics/pharmacology
- Analgesics, Opioid/antagonists & inhibitors
- Analgesics, Opioid/pharmacology
- Animals
- Binding Sites
- Binding, Competitive
- CHO Cells
- Cricetinae
- Cricetulus
- Drug Design
- Ligands
- Models, Molecular
- Molecular Sequence Data
- Morphinans/chemical synthesis
- Morphinans/pharmacology
- Morphine/antagonists & inhibitors
- Morphine/pharmacology
- Naltrexone/analogs & derivatives
- Naltrexone/chemical synthesis
- Naltrexone/pharmacology
- Radioligand Assay
- Receptors, Opioid, delta/antagonists & inhibitors
- Receptors, Opioid, kappa/antagonists & inhibitors
- Receptors, Opioid, mu/agonists
- Receptors, Opioid, mu/antagonists & inhibitors
- Sequence Alignment
- Structure-Activity Relationship
Collapse
Affiliation(s)
| | | | | | | | | | | | | | | | | | - Yan Zhang
- To whom correspondence should be addressed. Phone: 804-828-0021. Fax: 804-828-7625.
| |
Collapse
|
17
|
Conformationally constrained opioid ligands: the Dmt-Aba and Dmt-Aia versus Dmt-Tic scaffold. Bioorg Med Chem Lett 2008; 19:433-7. [PMID: 19062273 DOI: 10.1016/j.bmcl.2008.11.051] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2008] [Revised: 11/13/2008] [Accepted: 11/14/2008] [Indexed: 11/23/2022]
Abstract
Replacement of the constrained phenylalanine analogue 1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid (Tic) in the opioid Dmt-Tic-Gly-NH-Bn scaffold by the 4-amino-1,2,4,5-tetrahydro-indolo[2,3-c]azepin-3-one (Aia) and 4-amino-1,2,4,5-tetrahydro-2-benzazepin-3-one (Aba) scaffolds has led to the discovery of novel potent mu-selective agonists (Structures 5 and 12) as well as potent and selective delta-opioid receptor antagonists (Structures 9 and 15). Both stereochemistry and N-terminal N,N-dimethylation proved to be crucial factors for opioid receptor selectivity and functional bioactivity in the investigated small peptidomimetic templates. In addition to the in vitro pharmacological evaluation, automated docking models of Dmt-Tic and Dmt-Aba analogues were constructed in order to rationalize the observed structure-activity data.
Collapse
|
18
|
Dosen-Micovic L, Ivanovic M, Micovic V. Steric interactions and the activity of fentanyl analogs at the μ-opioid receptor. Bioorg Med Chem 2006; 14:2887-95. [PMID: 16376082 DOI: 10.1016/j.bmc.2005.12.010] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2005] [Revised: 11/24/2005] [Accepted: 12/02/2005] [Indexed: 01/07/2023]
Abstract
Fentanyl is a highly potent and clinically widely used narcotic analgesic. The synthesis of its analogs remains a challenge in the attempt to develop highly selective mu-opioid receptor agonists with specific pharmacological properties. In this paper, the use of flexible molecular docking in a study of the formation of complexes between a series of active fentanyl analogs and the mu-opioid receptor is described. The optimal position and orientation of fourteen fentanyl analogs in the binding pocket of the mu-receptor were determined. The major receptor amino acids and the ligand functional groups participating in the complex formation were identified. Stereochemical effects on the potency and binding are explained. The proposed model of ligand-receptor binding is in agreement with point mutation experiments explaining the role of the amino acids: Asp147, Tyr148, Asn230, His297, Trp318, His319, Cys321, and Tyr326 in the complex formation. In addition, the following amino acids were identified as being important for ligand binding or receptor activation: Ile322, Gly325, Val300, Met203, Leu200, Val143, and Ile144.
Collapse
|
19
|
Kane BE, Svensson B, Ferguson DM. Molecular recognition of opioid receptor ligands. AAPS JOURNAL 2006; 8:E126-37. [PMID: 16584119 PMCID: PMC2751431 DOI: 10.1208/aapsj080115] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The cloning of the opioid receptors and subsequent use of recombinant DNA technology have led to many new insights into ligand binding. Instead of focusing on the structural features that lead to increased affinity and selectivity, researchers are now able to focus on why these features are important. Site-directed mutagenesis and chimeric data have often been at the forefront in answering these questions. Herein, we survey pharmacophores of several opioid ligands in an effort to understand the structural requirements for ligand binding and selectivity. Models are presented and compared to illustrate key sites of recognition for both opiate and nonopiate ligands. The results indicate that different ligand classes may recognize different sites within the receptor, suggesting that multiple epitopes may exist for ligand binding and selectivity.
Collapse
Affiliation(s)
- Brian E. Kane
- College of Pharmacy, Department of Medicinal Chemistry, University of Minnesota, 308 Harvard St SE, 8-101 Weaver-Densford Hall, 55455 Minneapolis, MN
| | - Bengt Svensson
- College of Pharmacy, Department of Medicinal Chemistry, University of Minnesota, 308 Harvard St SE, 8-101 Weaver-Densford Hall, 55455 Minneapolis, MN
| | - David M. Ferguson
- College of Pharmacy, Department of Medicinal Chemistry, University of Minnesota, 308 Harvard St SE, 8-101 Weaver-Densford Hall, 55455 Minneapolis, MN
| |
Collapse
|
20
|
Pogozheva ID, Przydzial MJ, Mosberg HI. Homology modeling of opioid receptor-ligand complexes using experimental constraints. AAPS JOURNAL 2005; 7:E434-48. [PMID: 16353922 PMCID: PMC2750980 DOI: 10.1208/aapsj070243] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Opioid receptors interact with a variety of ligands, including endogenous peptides, opiates, and thousands of synthetic compounds with different structural scaffolds. In the absence of experimental structures of opioid receptors, theoretical modeling remains an important tool for structure-function analysis. The combination of experimental studies and modeling approaches allows development of realistic models of ligand-receptor complexes helpful for elucidation of the molecular determinants of ligand affinity and selectivity and for understanding mechanisms of functional agonism or antagonism. In this review we provide a brief critical assessment of the status of such theoretical modeling and describe some common problems and their possible solutions. Currently, there are no reliable theoretical methods to generate the models in a completely automatic fashion. Models of higher accuracy can be produced if homology modeling, based on the rhodopsin X-ray template, is supplemented by experimental structural constraints appropriate for the active or inactive receptor conformations, together with receptor-specific and ligand-specific interactions. The experimental constraints can be derived from mutagenesis and cross-linking studies, correlative replacements of ligand and receptor groups, and incorporation of metal binding sites between residues of receptors or receptors and ligands. This review focuses on the analysis of similarity and differences of the refined homology models of mu, delta, and kappa-opioid receptors in active and inactive states, emphasizing the molecular details of interaction of the receptors with some representative peptide and nonpeptide ligands, underlying the multiple modes of binding of small opiates, and the differences in binding modes of agonists and antagonists, and of peptides and alkaloids.
Collapse
Affiliation(s)
- Irina D Pogozheva
- Department of Medicinal Chemistry, College of Pharmacy, University of Michigan, Ann Arbor, MI 48109, USA
| | | | | |
Collapse
|
21
|
Zhang Y, Sham YY, Rajamani R, Gao J, Portoghese PS. Homology Modeling and Molecular Dynamics Simulations of the Mu Opioid Receptor in a Membrane-Aqueous System. Chembiochem 2005; 6:853-9. [PMID: 15776407 DOI: 10.1002/cbic.200400207] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Three types of opioid receptors-mu, delta, and kappa-belong to the rhodopsin subfamily in the G protein-coupled receptor superfamily. With the recent characterization of the high-resolution X-ray crystal structure of bovine rhodopsin, considerable attention has been focused on molecular modeling of these transmembrane proteins. In this study, a homology model of the mu opioid receptor was constructed based on the X-ray crystal structure of bovine rhodopsin. A phospholipid bilayer was built around the receptor, and two water layers were placed on both surfaces of the lipid bilayer. Molecular-dynamics simulations were carried out by using CHARMM for the entire system, which consisted of 316 amino acid residues, 92 phospholipid molecules, 8327 water molecules, and 11 chloride counter ions-40 931 atoms altogether. The whole system was equilibrated for 250 ps followed by another 2 ns dynamic simulation. The opioid ligand naltrexone was docked into the optimized model, and the critical amino acid residues for binding were identified. The mu opioid receptor homology model optimized in a complete membrane-aqueous system should provide a good starting point for further characterization of the binding modes for opioid ligands. Furthermore, the method developed herein will be applicable to molecular model building to other opioid receptors as well as other GPCRs.
Collapse
MESH Headings
- Animals
- Binding Sites
- Cattle
- Cell Membrane/chemistry
- Cell Membrane/metabolism
- Computer Simulation
- Crystallography, X-Ray
- Lipid Metabolism
- Lipids/chemistry
- Models, Molecular
- Naltrexone/analogs & derivatives
- Naltrexone/chemistry
- Naltrexone/pharmacology
- Protein Structure, Tertiary
- Receptors, Opioid, mu/antagonists & inhibitors
- Receptors, Opioid, mu/chemistry
- Receptors, Opioid, mu/metabolism
- Rhodopsin/chemistry
- Sequence Homology
- Solvents/chemistry
- Solvents/metabolism
- Structural Homology, Protein
- Water/chemistry
- Water/metabolism
Collapse
Affiliation(s)
- Yan Zhang
- Department of Medicinal Chemistry, University of Minnesota, Minneapolis, MN 55455, USA.
| | | | | | | | | |
Collapse
|
22
|
Meurisse R, Brasseur R, Thomas A. Aromatic side-chain interactions in proteins. Near- and far-sequence His-X pairs. BIOCHIMICA ET BIOPHYSICA ACTA 2003; 1649:85-96. [PMID: 12818194 DOI: 10.1016/s1570-9639(03)00161-4] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Several studies have analysed aromatic interactions, involving mostly phenylalanine, tyrosine and tryptophan. Only a few studies have considered histidine as an interacting aromatic residue. An extensive analysis of aromatic His-X interactions is performed here on a data set of 593 PDB structures: 68% of the histidine are involved in aromatic pairs and 1271 non-redundant His-X pairs were analysed. Thirty percent of these pairs involve an aromatic partner less than 6 apart in the sequence. These near-sequence pairs correspond to conformations which stabilise secondary structures, mainly alpha-helices when the residues are 4 apart and beta-strands when they are 2 apart in the sequence. The partners of the other His-X pairs (887, 70%) are more than 5 apart in the sequence. Of these far-sequence pairs, 35% bridge beta strands and only 9% helices. The near-sequence pairs are sterically constrained as supported by conformer distribution. The X partners of far-sequence His-X pairs are mainly "above" the histidine ring with tilted and normal rings, corresponding to a "T shape; face to edge" orientation. Phenylalanine, the only aromatic residue with no heteroatom, is a disfavoured partner, whereas histidine is the preferred one. Heteroatom-heteroatom interactions are favoured in near-sequence as well as in far-sequence His-His, His-Trp and His-Tyr pairs.
Collapse
Affiliation(s)
- Rita Meurisse
- Centre de Biophysique Moléculaire Numérique (CBMN), 2, Passage des déportés, Faculté Scientifique Agronomique de Gembloux (FSAGx), Gembloux 5030, Belgium
| | | | | |
Collapse
|
23
|
Medzihradszky K. Josef Rudinger Memorial Lecture 2002. The chemistry of the opioid receptor binding sites. J Pept Sci 2003; 9:333-53. [PMID: 12846480 DOI: 10.1002/psc.469] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Since the discovery of the opioid receptors and their endogenous ligands an immense research work has been devoted to the exploration of their specificity, the mechanism of ligand binding and ligand-receptor interactions. One of the main goals has been the location and characterization of the binding sites. The present review compiles the results achieved in this field in the last quarter of a century, and puts some questions concerning the success of these efforts.
Collapse
Affiliation(s)
- Kálmán Medzihradszky
- Research Group of Peptide Chemistry, Hungarian Academy of Sciences, Budapest, Hungary.
| |
Collapse
|
24
|
Pil J, Tytgat J. Serine 329 of the mu-opioid receptor interacts differently with agonists. J Pharmacol Exp Ther 2003; 304:924-30. [PMID: 12604666 DOI: 10.1124/jpet.102.040113] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
To investigate the effect of the hydrophilic Ser amino acid in position 329 of the human mu-opioid receptor (hMORwt) on the potency of various agonists, we mutated this residue to Ala (hMORS329A). Taking advantage of the functional coupling of the opioid receptor with the heteromultimeric G-protein-coupled inwardly rectifying potassium channel (GIRK1/GIRK2), either the wild-type hMOR or the mutated receptor (hMORS329A) was functionally coexpressed with GIRK1 and GIRK2 channels together with a regulator of G-protein signaling (RGS4) in Xenopus laevis oocytes. The two-microelectrode voltage-clamp technique was used to measure the opioid receptor activated GIRK1/GIRK2 channel responses. The potency of the peptide agonist [D-Ala(2),N-MePhe(4),Gly(5)-ol]-enkephalin (DAMGO) decreased as measured via hMORS329A, whereas the potency of nonpeptide agonists like morphine, fentanyl, and beta-hydroxyfentanyl (R004333) increased via the mutated receptor. Our results are indicative for the existence of hydrophilic interactions between Ser(329) and DAMGO, thereby decreasing the potency of DAMGO via the mutated receptor, whereas hydrophobic interactions between the mutated receptor and the N-phenylethyl of morphine and fentanyl can explain the increased potency. We conclude that the hydroxyl group of Ser(329) is not involved in the formation of a hydrogen bond with the beta-hydroxy group of fentanyl and that mutation of this residue to alanine caused dual effects depending on the nature of the ligand.
Collapse
Affiliation(s)
- Joost Pil
- Laboratory of Toxicology, Faculty of Pharmaceutical Sciences, University of Leuven, Leuven, Belgium
| | | |
Collapse
|
25
|
Abstract
Opioid analgesics provide outstanding benefits for relief of severe pain. The mechanisms of the analgesia accompanied with some side effects have been investigated by many scientists to shed light on the complex biological processes at the molecular level. New opioid drugs and therapies with more desirable properties can be developed on the bases of accurate insight of the opioid ligand-receptor interaction and clear knowledge of the pharmacological behavior of opioid receptors and the associated proteins. Toward this goal, recent advances in selective opioid receptor agonists and antagonists including opioid ligand-receptor interactions are summarized in this review article.
Collapse
Affiliation(s)
- Masakatsu Eguchi
- Pacific Northwest Research Institute, 720 Broadway, Seattle, Washington 98122, USA.
| |
Collapse
|
26
|
Abstract
The sequencing of the human genome is only the first step. The next step is to determine the function of these genes and in particular, how alterations in specific genes lead to major human disorders. Many laboratories are now focusing on identifying and characterizing single nucleotide polymorphisms (SNPs), to determine which correlate in frequency with certain population groups who may be particularly susceptible to certain diseases. The mu opioid receptor (MOR), which mediates the clinically important analgesic effects of drugs like morphine as well as the euphoria sought by heroin abusers, exhibits several dozen polymorphisms. Several of these are associated with altered receptor function and individuals at risk for drug abuse.
Collapse
Affiliation(s)
- Nancy M Lee
- California Pacific Medical Center Research Institute, 2330 Clay Street, Stern Bldg., San Francisco, CA 94115, USA.
| | | |
Collapse
|
27
|
Chavkin C, McLaughlin JP, Celver JP. Regulation of opioid receptor function by chronic agonist exposure: constitutive activity and desensitization. Mol Pharmacol 2001; 60:20-5. [PMID: 11408596 DOI: 10.1124/mol.60.1.20] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Affiliation(s)
- C Chavkin
- Department of Pharmacology, University of Washington, Seattle, Washington 98195-7280, USA.
| | | | | |
Collapse
|
28
|
Xu H, Lu YF, Thomas JB, Carroll FI, Rice KC, Rothman RB. Opioid peptide receptor studies. 15. Relative efficacy of 4-[(N-allyl-3-methyl-4-piperidinyl)phenylamino]-N,N-diethylbenzamide and related compounds at the cloned human delta-opioid receptor. Synapse 2001; 40:269-74. [PMID: 11309842 DOI: 10.1002/syn.1049] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Previous data obtained from both binding and functional assays demonstrated that (-)-4-[(N-allyl-3-methyl-4-piperidinyl)phenylamino]-N,N-diethylbenzamide [(-)-RTI5989-54] displays selective binding and full agonist activity relative to (+/-)-RTI5989-54 for the delta opioid receptor. The present study was conducted to evaluate the activities of structurally diverse opioid receptor delta ligands in the [(35)S]GTP-gamma-S binding assay, comparing the relationship between receptor binding, activation, efficacy, and intrinsic efficacy. The data, obtained with cloned human delta receptors, demonstrated that (-)-RTI5989-54 behaves like the highly selective delta agonist SNC80. Addition of the hydroxyl group to RTI5989-54 (RTI5989-61) or replacement of the allyl group with the trans-crotyl group on the piperidine nitrogen of RTI-5989-61 (RTI5989-62) increased binding affinity, produced full agonist activity, and decreased intrinsic efficacy at the delta opioid receptor. The order of potency for the EC(50) (GTP-gamma-S) was RTI5989-62 (0.20 nM) > RTI5989-61 (0.43 nM) > SNC80 (1.92 nM) > DPDPE (3.50 nM) > (-)-RTI5989-54 (17.6 nM) > (+/-)-RTI5989-54 (65.6 nM) > (+)-RTI5989-54 (483 nM). RTI5989-61 and RTI5989-62 were fully efficacious, but had intrinsic efficacy values that were 2.2-3.1 times lower than that of DPDPE and SNC80. Comparison of the binding K(i) in competitively inhibiting [(125)I]IOXY binding to the functional K(i) for delta antagonists [Ki (IOXY)/Ki (GTP-gamma-S)] shows that antagonists might antagonize agonist-evoked neurochemical effects with equal magnitude while occupying different proportions of target receptors.
Collapse
Affiliation(s)
- H Xu
- CPS, NIDA, IRP, NIDA, NIH, Baltimore, Maryland 21224, USA
| | | | | | | | | | | |
Collapse
|
29
|
Xu H, Hashimoto A, Rice KC, Jacobson AE, Thomas JB, Carroll FI, Lai J, Rothman RB. Opioid peptide receptor studies. 14. Stereochemistry determines agonist efficacy and intrinsic efficacy in the [(35)S]GTP-gamma-S functional binding assay. Synapse 2001; 39:64-9. [PMID: 11071711 DOI: 10.1002/1098-2396(20010101)39:1<64::aid-syn9>3.0.co;2-j] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Previous data obtained with the cloned rat mu opioid receptor demonstrated that stereochemistry affects the four parameters of the ligand-receptor interaction: potency (ED(50)), efficacy (maximal stimulation), intrinsic efficacy (effect as a function of receptor occupation), and binding affinity. This study evaluated the activities of structurally diverse opioid receptor ligands in the [(35)S]GTP-gamma-S binding assay, comparing the relationship between receptor binding, activation, efficacy, and intrinsic efficacy. The data, obtained with cloned rat mu receptors, demonstrated that an analgetic, (-)-5-m-hydroxyphenyl-2-methylmorphan (NIH8508), and its (+)-isomer (NIH8509), behave as partial agonists, but had different intrinsic efficacy in the [(35)S]GTP-gamma-S binding assay. Replacement of the methyl group with the phenethyl group on the piperidine nitrogen of NIH8508 and NIH8509 [(1R,5S)-AH019 and (1S, 5R)-AH019] increased affinity for the mu receptor and eliminated any agonist effect, supporting the hypothesis that certain structural features make these compounds antagonists. These study also show that all of the fully efficacious mu agonists studied here had high levels of intrinsic efficacy, producing a 50% response at about 10% receptor occupancy. Comparison of the binding K(i) in competitively inhibiting [(125)I]IOXY binding to the functional K(i) for opioid antagonists [K(i)(IOXY)/K(i)(GTP-gamma-S)] provides more detailed evidence that the [(35)S]GTP-gamma-S binding assay can be used to reliably determine apparent functional antagonist K(i) values in addition to agonist ED(50), efficacy and intrinsic efficacy.
Collapse
Affiliation(s)
- H Xu
- CPS, DIR, NIDA, Baltimore, Maryland 21224, USA
| | | | | | | | | | | | | | | |
Collapse
|
30
|
Bonner G, Meng F, Akil H. Selectivity of mu-opioid receptor determined by interfacial residues near third extracellular loop. Eur J Pharmacol 2000; 403:37-44. [PMID: 10969141 DOI: 10.1016/s0014-2999(00)00578-1] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We hypothesized that the selectivity profile of the rat mu-opioid receptor for opioid receptor-selective ligands is determined by the nature of the amino acid residues at highly divergent sites in the ligand-binding pocket. To determine which characteristics of these residues contribute to opioid receptor ligand selectivity, we made various mutant receptors that replaced the Lys(303) and Trp(318) residues near the extracellular interface of transmembrane domains VI and VII, respectively. Ligand binding determinations using transiently transfected monkey kidney epithelial (COS-1) cells show that Lys(303) mutations cause little change in the receptor binding profile, whereas the Trp(318) mutant receptors have considerably lower affinity for micro-opioid receptor-selective ligands and greatly increased affinity for delta-opioid receptor-selective ligands. The nature of these mutations show that this effect is not due to sterics or charge alone. [35S]guanosine-5'-O-(3-thio)-triphosphate ([35S]GTPgammaS) activity assays show that these residues may influence functional, as well as binding selection. We conclude that a primary role for Trp(318) is to form a basis for ligand selectivity.
Collapse
MESH Headings
- Amino Acid Substitution
- Animals
- Benzamides/metabolism
- Benzamides/pharmacology
- Benzomorphans/metabolism
- Benzomorphans/pharmacology
- Binding Sites/genetics
- Binding, Competitive/drug effects
- COS Cells
- Enkephalin, Ala(2)-MePhe(4)-Gly(5)-/metabolism
- Enkephalin, Ala(2)-MePhe(4)-Gly(5)-/pharmacology
- Enkephalin, D-Penicillamine (2,5)-/metabolism
- Enkephalin, D-Penicillamine (2,5)-/pharmacology
- Fentanyl/metabolism
- Fentanyl/pharmacology
- Guanosine 5'-O-(3-Thiotriphosphate)/metabolism
- Ligands
- Morphine/metabolism
- Morphine/pharmacology
- Mutation
- Naloxone/analogs & derivatives
- Naloxone/metabolism
- Naloxone/pharmacology
- Naltrexone/analogs & derivatives
- Naltrexone/metabolism
- Naltrexone/pharmacology
- Narcotic Antagonists/metabolism
- Narcotic Antagonists/pharmacology
- Peptides/metabolism
- Peptides/pharmacology
- Piperazines/metabolism
- Piperazines/pharmacology
- Protein Conformation
- Radioligand Assay
- Rats
- Receptors, Opioid, mu/chemistry
- Receptors, Opioid, mu/genetics
- Receptors, Opioid, mu/metabolism
- Signal Transduction
- Sulfur Radioisotopes
Collapse
Affiliation(s)
- G Bonner
- Mental Health Research Institute, University of Michigan, Ann Arbor 48109-0720, USA.
| | | | | |
Collapse
|