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Schrader TO, Lorrain KI, Bagnol D, Edu GC, Broadhead A, Baccei C, Poon MM, Stebbins KJ, Xiong Y, Lorenzana AO, Chan JR, Green AJ, Lorrain DS, Chen A. Identification and In Vivo Evaluation of Myelination Agent PIPE-3297, a Selective Kappa Opioid Receptor Agonist Devoid of β-Arrestin-2 Recruitment Efficacy. ACS Chem Neurosci 2024; 15:685-698. [PMID: 38265210 DOI: 10.1021/acschemneuro.3c00807] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2024] Open
Abstract
Structure-activity relationship studies led to the discovery of PIPE-3297, a fully efficacious and selective kappa opioid receptor (KOR) agonist. PIPE-3297, a potent activator of G-protein signaling (GTPγS EC50 = 1.1 nM, 91% Emax), did not elicit a β-arrestin-2 recruitment functional response (Emax < 10%). Receptor occupancy experiments performed with the novel KOR radiotracer [3H]-PIPE-3113 revealed that subcutaneous (s.c.) administration of PIPE-3297 at 30 mg/kg in mice achieved 90% occupancy of the KOR in the CNS 1 h post dose. A single subcutaneous dose of PIPE-3297 in healthy mice produced a statistically significant increase of mature oligodendrocytes (P < 0.0001) in the KOR-enriched striatum, an effect that was not observed in animals predosed with the selective KOR antagonist norbinaltorphimine. An equivalent dose given to mice in an open-field activity-monitoring system revealed a small KOR-independent decrease in total locomotor activity versus vehicle measured between 60 and 75 min post dose. Daily doses of PIPE-3297 at both 3 and 30 mg/kg s.c. reduced the disease score in the mouse experimental autoimmune encephalomyelitis (EAE) model. Visually evoked potential (VEP) N1 latencies were also significantly improved versus vehicle in both dose groups, and latencies matched those of untreated animals. Taken together, these findings highlight the potential therapeutic value of functionally selective G-protein KOR agonists in demyelinating disease, which may avoid the sedating side effects typically associated with classical nonbiased KOR agonists.
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Affiliation(s)
- Thomas O Schrader
- Contineum Therapeutics, Suite 200, 10578 Science Center Drive, San Diego, California 92121, United States
| | - Kym I Lorrain
- Contineum Therapeutics, Suite 200, 10578 Science Center Drive, San Diego, California 92121, United States
| | - Didier Bagnol
- Contineum Therapeutics, Suite 200, 10578 Science Center Drive, San Diego, California 92121, United States
| | - Geraldine C Edu
- Contineum Therapeutics, Suite 200, 10578 Science Center Drive, San Diego, California 92121, United States
| | - Alexander Broadhead
- Contineum Therapeutics, Suite 200, 10578 Science Center Drive, San Diego, California 92121, United States
| | - Christopher Baccei
- Contineum Therapeutics, Suite 200, 10578 Science Center Drive, San Diego, California 92121, United States
| | - Michael M Poon
- Contineum Therapeutics, Suite 200, 10578 Science Center Drive, San Diego, California 92121, United States
| | - Karin J Stebbins
- Contineum Therapeutics, Suite 200, 10578 Science Center Drive, San Diego, California 92121, United States
| | - Yifeng Xiong
- Contineum Therapeutics, Suite 200, 10578 Science Center Drive, San Diego, California 92121, United States
| | - Ariana O Lorenzana
- Contineum Therapeutics, Suite 200, 10578 Science Center Drive, San Diego, California 92121, United States
| | - Jonah R Chan
- Department of Neurology, University of California, San Francisco, San Francisco, California 94143, United States
| | - Ari J Green
- Department of Neurology, University of California, San Francisco, San Francisco, California 94143, United States
| | - Daniel S Lorrain
- Contineum Therapeutics, Suite 200, 10578 Science Center Drive, San Diego, California 92121, United States
| | - Austin Chen
- Contineum Therapeutics, Suite 200, 10578 Science Center Drive, San Diego, California 92121, United States
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Lohman RJ, Reddy Tupally K, Kandale A, Cabot PJ, Parekh HS. Design and development of novel, short, stable dynorphin-based opioid agonists for safer analgesic therapy. Front Pharmacol 2023; 14:1150313. [PMID: 36937883 PMCID: PMC10020352 DOI: 10.3389/fphar.2023.1150313] [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: 01/24/2023] [Accepted: 02/15/2023] [Indexed: 03/06/2023] Open
Abstract
Kappa opioid receptors have exceptional potential as an analgesic target, seemingly devoid of many problematic Mu receptor side-effects. Kappa-selective, small molecule pharmaceutical agents have been developed, but centrally mediated side-effects limit clinical translation. We modify endogenous dynorphin peptides to improve drug-likeness and develop safer KOP receptor agonists for clinical use. Using rational, iterative design, we developed a series of potent, selective, and metabolically stable peptides from dynorphin 1-7. Peptides were assessed for in vitro cAMP-modulation against three opioid receptors, metabolic stability, KOP receptor selectivity, desensitisation and pERK-signalling capability. Lead peptides were evaluated for in vivo efficacy in a rat model of inflammatory nociception. A library of peptides was synthesised and assessed for pharmacological and metabolic stability. Promising peptide candidates showed low nanomolar KOP receptor selectivity in cAMP assay, and improved plasma and trypsin stability. Selected peptides showed bias towards cAMP signalling over pERK activity, also demonstrating reduced desensitisation. In vivo, two peptides showed significant opioid-like antinociception comparable to morphine and U50844H. These highly potent and metabolically stable peptides are promising opioid analgesic leads for clinical translation. Since they are somewhat biased peptide Kappa agonists they may lack many significant side-effects, such as tolerance, addiction, sedation, and euphoria/dysphoria, common to opioid analgesics.
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Evaluation of the Intracellular Signaling Activities of κ-Opioid Receptor Agonists, Nalfurafine Analogs; Focusing on the Selectivity of G-Protein- and β-Arrestin-Mediated Pathways. Molecules 2022; 27:molecules27207065. [PMID: 36296658 PMCID: PMC9611050 DOI: 10.3390/molecules27207065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2022] [Revised: 10/15/2022] [Accepted: 10/18/2022] [Indexed: 12/30/2022] Open
Abstract
Opioid receptors (ORs) are classified into three types (μ, δ, and κ), and opioid analgesics are mainly mediated by μOR activation; however, their use is sometimes restricted by unfavorable effects. The selective κOR agonist nalfurafine was initially developed as an analgesic, but its indication was changed because of the narrow safety margin. The activation of ORs mainly induces two intracellular signaling pathways: a G-protein-mediated pathway and a β-arrestin-mediated pathway. Recently, the expectations for κOR analgesics that selectively activate these pathways have increased; however, the structural properties required for the selectivity of nalfurafine are still unknown. Therefore, we evaluated the partial structures of nalfurafine that are necessary for the selectivity of these two pathways. We assayed the properties of nalfurafine and six nalfurafine analogs (SYKs) using cells stably expressing κORs. The SYKs activated κORs in a concentration-dependent manner with higher EC50 values than nalfurafine. Upon bias factor assessment, only SYK-309 (possessing the 3S-hydroxy group) showed higher selectivity of G-protein-mediated signaling activities than nalfurafine, suggesting the direction of the 3S-hydroxy group may affect the β-arrestin-mediated pathway. In conclusion, nalfurafine analogs having a 3S-hydroxy group, such as SYK-309, could be considered G-protein-biased κOR agonists.
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Khan MIH, Sawyer BJ, Akins NS, Le HV. A systematic review on the kappa opioid receptor and its ligands: New directions for the treatment of pain, anxiety, depression, and drug abuse. Eur J Med Chem 2022; 243:114785. [PMID: 36179400 DOI: 10.1016/j.ejmech.2022.114785] [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: 07/08/2022] [Revised: 09/16/2022] [Accepted: 09/16/2022] [Indexed: 11/29/2022]
Abstract
Kappa opioid receptor (KOR) is a member of the opioid receptor system, the G protein-coupled receptors that are expressed throughout the peripheral and central nervous systems and play crucial roles in the modulation of antinociception and a variety of behavioral states like anxiety, depression, and drug abuse. KOR agonists are known to produce potent analgesic effects and have been used clinically for the treatment of pain, while KOR antagonists have shown efficacy in the treatment of anxiety and depression. This review summarizes the history, design strategy, discovery, and development of KOR ligands. KOR agonists are classified as non-biased, G protein-biased, and β-arrestin recruitment-biased, according to their degrees of bias. The mechanisms and associated effects of the G protein signaling pathway and β-arrestin recruitment signaling pathway are also discussed. Meanwhile, KOR antagonists are classified as long-acting and short-acting, based on their half-lives. In addition, we have special sections for mixed KOR agonists and selective peripheral KOR agonists. The mechanisms of action and pharmacokinetic, pharmacodynamic, and behavioral studies for each of these categories are also discussed in this review.
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Affiliation(s)
- Md Imdadul H Khan
- Department of BioMolecular Sciences and Research Institute of Pharmaceutical Sciences, School of Pharmacy, University of Mississippi, University, MS, 38677, USA
| | - Benjamin J Sawyer
- Department of BioMolecular Sciences and Research Institute of Pharmaceutical Sciences, School of Pharmacy, University of Mississippi, University, MS, 38677, USA
| | - Nicholas S Akins
- Department of BioMolecular Sciences and Research Institute of Pharmaceutical Sciences, School of Pharmacy, University of Mississippi, University, MS, 38677, USA
| | - Hoang V Le
- Department of BioMolecular Sciences and Research Institute of Pharmaceutical Sciences, School of Pharmacy, University of Mississippi, University, MS, 38677, USA.
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Chen C, Huang P, Bland K, Li M, Zhang Y, Liu-Chen LY. Agonist-Promoted Phosphorylation and Internalization of the Kappa Opioid Receptor in Mouse Brains: Lack of Connection With Conditioned Place Aversion. Front Pharmacol 2022; 13:835809. [PMID: 35652052 PMCID: PMC9149264 DOI: 10.3389/fphar.2022.835809] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Accepted: 01/31/2022] [Indexed: 12/30/2022] Open
Abstract
Selective kappa opioid receptor (KOR) agonists are promising antipruritic agents and analgesics. However, clinical development of KOR agonists has been limited by side effects, including psychotomimetic effects, dysphoria, and sedation, except for nalfurafine, and recently. CR845 (difelikefalin). Activation of KOR elicits G protein- and β-arrestin-mediated signaling. KOR-induced analgesic and antipruritic effects are mediated by G protein signaling. However, different results have been reported as to whether conditioned place aversion (CPA) induced by KOR agonists is mediated by β-arrestin signaling. In this study, we examined in male mice if there was a connection between agonist-promoted CPA and KOR phosphorylation and internalization, proxies for β-arrestin recruitment in vivo using four KOR agonists. Herein, we demonstrated that at doses producing maximal effective analgesic and antiscratch effects, U50,488H, MOM-SalB, and 42B, but not nalfurafine, promoted KOR phosphorylation at T363 and S369 in mouse brains, as detected by immunoblotting with phospho-KOR-specific antibodies. In addition, at doses producing maximal effective analgesic and antiscratch effects, U50,488H, MOM-SalB, and 42B, but not nalfurafine, caused KOR internalization in the ventral tegmental area of a mutant mouse line expressing a fusion protein of KOR conjugated at the C-terminus with tdTomato (KtdT). We have reported previously that the KOR agonists U50,488H and methoxymethyl salvinorin B (MOM-SalB) cause CPA, whereas nalfurafine and 42B do not, at doses effective for analgesic and antiscratch effects. Taken together, these data reveal a lack of connection between agonist-promoted KOR-mediated CPA with agonist-induced KOR phosphorylation and internalization in male mice.
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Affiliation(s)
- Chongguang Chen
- Center for Substance Abuse Research and Department of Neural Sciences, Temple University Lewis Katz School of Medicine, Philadelphia, PA, United States
| | - Peng Huang
- Center for Substance Abuse Research and Department of Neural Sciences, Temple University Lewis Katz School of Medicine, Philadelphia, PA, United States
| | - Kathryn Bland
- Center for Substance Abuse Research and Department of Neural Sciences, Temple University Lewis Katz School of Medicine, Philadelphia, PA, United States
| | - Mengchu Li
- Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, Richmond, VA, United States
| | - Yan Zhang
- Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, Richmond, VA, United States
| | - Lee-Yuan Liu-Chen
- Center for Substance Abuse Research and Department of Neural Sciences, Temple University Lewis Katz School of Medicine, Philadelphia, PA, United States
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Sturaro C, Malfacini D, Argentieri M, Djeujo FM, Marzola E, Albanese V, Ruzza C, Guerrini R, Calo’ G, Molinari P. Pharmacology of Kappa Opioid Receptors: Novel Assays and Ligands. Front Pharmacol 2022; 13:873082. [PMID: 35529436 PMCID: PMC9068900 DOI: 10.3389/fphar.2022.873082] [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: 02/10/2022] [Accepted: 03/24/2022] [Indexed: 11/13/2022] Open
Abstract
The present study investigated the in vitro pharmacology of the human kappa opioid receptor using multiple assays, including calcium mobilization in cells expressing chimeric G proteins, the dynamic mass redistribution (DMR) label-free assay, and a bioluminescence resonance energy transfer (BRET) assay that allows measurement of receptor interaction with G protein and β-arrestin 2. In all assays, dynorphin A, U-69,593, and [D-Pro10]dyn(1-11)-NH2 behaved as full agonists with the following rank order of potency [D-Pro10]dyn(1-11)-NH2 > dynorphin A ≥ U-69,593. [Dmt1,Tic2]dyn(1-11)-NH2 behaved as a moderate potency pure antagonist in the kappa-β-arrestin 2 interaction assay and as low efficacy partial agonist in the other assays. Norbinaltorphimine acted as a highly potent and pure antagonist in all assays except kappa-G protein interaction, where it displayed efficacy as an inverse agonist. The pharmacological actions of novel kappa ligands, namely the dynorphin A tetrameric derivative PWT2-Dyn A and the palmitoylated derivative Dyn A-palmitic, were also investigated. PWT2-Dyn A and Dyn A-palmitic mimicked dynorphin A effects in all assays showing similar maximal effects but 3–10 fold lower potency. In conclusion, in the present study, multiple in vitro assays for the kappa receptor have been set up and pharmacologically validated. In addition, PWT2-Dyn A and Dyn A-palmitic were characterized as potent full agonists; these compounds are worthy of further investigation in vivo for those conditions in which the activation of the kappa opioid receptor elicits beneficial effects e.g. pain and pruritus.
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Affiliation(s)
- Chiara Sturaro
- Department of Neuroscience and Rehabilitation, Section of Pharmacology, University of Ferrara, Ferrara, Italy
| | - Davide Malfacini
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Padova, Italy
- *Correspondence: Davide Malfacini,
| | - Michela Argentieri
- Department of Neuroscience and Rehabilitation, Section of Pharmacology, University of Ferrara, Ferrara, Italy
| | - Francine M. Djeujo
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Padova, Italy
| | - Erika Marzola
- Department of Chemical, Pharmaceutical and Agricultural Sciences, University of Ferrara, Ferrara, Italy
| | - Valentina Albanese
- Department of Chemical, Pharmaceutical and Agricultural Sciences, University of Ferrara, Ferrara, Italy
| | - Chiara Ruzza
- Department of Neuroscience and Rehabilitation, Section of Pharmacology, University of Ferrara, Ferrara, Italy
- Technopole of Ferrara, LTTA Laboratory for Advanced Therapies, Ferrara, Italy
| | - Remo Guerrini
- Department of Chemical, Pharmaceutical and Agricultural Sciences, University of Ferrara, Ferrara, Italy
- Technopole of Ferrara, LTTA Laboratory for Advanced Therapies, Ferrara, Italy
| | - Girolamo Calo’
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Padova, Italy
| | - Paola Molinari
- National Center for Drug Research and Evaluation, National Institute of Health, Rome, Italy
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7
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French AR, van Rijn RM. An updated assessment of the translational promise of G-protein-biased kappa opioid receptor agonists to treat pain and other indications without debilitating adverse effects. Pharmacol Res 2022; 177:106091. [PMID: 35101565 PMCID: PMC8923989 DOI: 10.1016/j.phrs.2022.106091] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 01/14/2022] [Accepted: 01/18/2022] [Indexed: 01/22/2023]
Abstract
Kappa opioid receptor (κOR) agonists lack the abuse liability and respiratory depression effects of clinically used mu opioid receptor (μOR) analgesics and are hypothesized to be safer alternatives. However, κOR agonists have limiting adverse effects of their own, including aversion, sedation, and mood effects, that have hampered their clinical translation. Studies performed over the last 15 years have suggested that these adverse effects could result from activation of distinct intracellular signaling pathways that are dependent on β-arrestin, whereas signaling downstream of G protein activation produces antinociception. This led to the hypothesis that agonists biased away from β-arrestin signaling would have improved therapeutic windows over traditional unbiased agonists and allow for clinical development of analgesic G-protein-biased κOR agonists. Given a recent controversy regarding the benefits of G-protein-biased μOR agonists, it is timely to reassess the therapeutic promise of G-protein-biased κOR agonists. Here we review recent discoveries from preclinical κOR studies and critically evaluate the therapeutic windows of G-protein-biased κOR agonists in each of the adverse effects above. Overall, we find that G-protein-biased κOR agonists generally have improved therapeutic window relative to unbiased agonists, although frequently study design limits strong conclusions in this regard. However, a steady flow of newly developed biased κOR agonists paired with recently engineered behavioral and molecular tools puts the κOR field in a prime position to make major advances in our understanding of κOR function and fulfill the promise of translating a new generation of biased κOR agonists to the clinic.
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Affiliation(s)
- Alexander R French
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN 47907, USA; Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN 47907, USA
| | - Richard M van Rijn
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN 47907, USA; Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN 47907, USA; Purdue Institute for Drug Discovery, Purdue University, West Lafayette, IN 47907, USA.
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8
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Chakraborty S, Majumdar S. Natural Products for the Treatment of Pain: Chemistry and Pharmacology of Salvinorin A, Mitragynine, and Collybolide. Biochemistry 2021; 60:1381-1400. [PMID: 32930582 PMCID: PMC7982354 DOI: 10.1021/acs.biochem.0c00629] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Pain remains a very pervasive problem throughout medicine. Classical pain management is achieved through the use of opiates belonging to the mu opioid receptor (MOR) class, which have significant side effects that hinder their utility. Pharmacologists have been trying to develop opioids devoid of side effects since the isolation of morphine from papaver somniferum, more commonly known as opium by Sertürner in 1804. The natural products salvinorin A, mitragynine, and collybolide represent three nonmorphinan natural product-based targets, which are potent selective agonists of opioid receptors, and emerging next-generation analgesics. In this work, we review the phytochemistry and medicinal chemistry efforts on these templates and their effects on affinity, selectivity, analgesic actions, and a myriad of other opioid-receptor-related behavioral effects.
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Affiliation(s)
- Soumen Chakraborty
- Center for Clinical Pharmacology, St. Louis College of Pharmacy and Washington University School of Medicine, St. Louis, Missouri 63110, United States; Department of Anesthesiology, Washington University School of Medicine, St. Louis, Missouri 63110, United States
| | - Susruta Majumdar
- Center for Clinical Pharmacology, St. Louis College of Pharmacy and Washington University School of Medicine, St. Louis, Missouri 63110, United States; Department of Anesthesiology, Washington University School of Medicine, St. Louis, Missouri 63110, United States
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9
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Marmolejo-Valencia AF, Madariaga-Mazón A, Martinez-Mayorga K. Bias-inducing allosteric binding site in mu-opioid receptor signaling. SN APPLIED SCIENCES 2021. [DOI: 10.1007/s42452-021-04505-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
Abstract
G-protein-biased agonism of the mu-opioid receptor (μ-OR) is emerging as a promising strategy in analgesia. A deep understanding of how biased agonists modulate and differentiate G-protein-coupled receptors (GPCR) signaling pathways and how this is transferred into the cell are open questions. Here, using extensive all-atom molecular dynamics simulations, we analyzed the binding recognition process and signaling effects of three prototype μ-OR agonists. Our suggested structural mechanism of biased signaling in μ-OR involves an allosteric sodium ion site, water networks, conformational rearrangements in conserved motifs and collective motions of loops and transmembrane helices. These analyses led us to highlight the relevance of a bias-inducing allosteric binding site in the understanding of μ-OR’s G-protein-biased signaling. These results also suggest a competitive equilibrium between the agonists and the allosteric sodium ion, where the bias-inducing allosteric binding site can be modulated by this ion or an agonist such as herkinorin. Notably, herkinorin arises as the archetype modulator of μ-OR and its interactive pattern could be used for screening efforts via protein–ligand interaction fingerprint (PLIF) studies.
Article highlights
Agonists and a sodium ion compete for the bias-inducing allosteric binding site that modulates signaling in mu-opioid receptors.
Molecular dynamics simulations of the prototype μ-OR agonist suggest a competitive equilibrium involving the agonist and an allosteric sodium ion.
Analysis of experimental data from the literature and molecular models provides the structural bases of biased agonism on μ-OR.
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NB-33, a bioreversible opioid derivative of Nalbuphine, shows enhanced pharmacodynamics. Eur J Pharm Sci 2021; 159:105734. [PMID: 33515698 DOI: 10.1016/j.ejps.2021.105734] [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: 09/23/2020] [Revised: 01/15/2021] [Accepted: 01/21/2021] [Indexed: 11/22/2022]
Abstract
Developing non-addictive and safer opioids for pain management is unmet medical need. Among a number of bioreversible derivatives of Nalbuphine - an equipotent to morphine opioid without serious side effects - NB-33 was identified in silico and confirmed in vivo as a superior analgesic agent. Apart from enhanced pharmacodynamics profile, NB-33 outperformed the parent compound on equimolar bases in cold ethanol tail-flick and mechanical models of pain in rats. With no β-arrestin engagement liability, good stability in simulated gastro-intestinal fluid and slow release of Nalbuphine by plasma NB-33 is being developed as an oral and safer alternative of its parent drug.
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Ju ZH, Liang X, Ren YY, Shu LW, Yan YH, Cui X. Neurons derived from human-induced pluripotent stem cells express mu and kappa opioid receptors. Neural Regen Res 2021; 16:653-658. [PMID: 33063716 PMCID: PMC8067944 DOI: 10.4103/1673-5374.295341] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Neuroprotection studies have shown that induced pluripotent stem (iPS) cells have the possibility to transform neuroprotection research. In the present study, iPS cells were generated from human renal epithelial cells and were then differentiated into neurons. Cells in the iPS-cell group were maintained in stem cell medium. In contrast, cells in the iPS-neuron group were first maintained in neural induction medium and expansion medium containing ROCK inhibitors, and then cultivated in neuronal differentiation medium and neuronal maturation medium to induce the neural stem cells to differentiate into neurons. The expression of relevant markers was compared at different stages of differentiation. Immunofluorescence staining revealed that cells in the iPS-neuron group expressed the neural stem cell markers SOX1 and nestin on day 11 of induction, and neuronal markers TUBB3 and NeuN on day 21 of induction. Polymerase chain reaction results demonstrated that, compared with the iPS-cell group, TUBB3 gene expression in the iPS-neuron group was increased 15.6-fold. Further research revealed that, compared with the iPS-cell group, the gene expression and immunoreactivity of mu opioid receptor in the iPS-neuron group were significantly increased (38.3-fold and 5.7-fold, respectively), but those of kappa opioid receptor had only a slight change (1.33-fold and 1.57-fold increases, respectively). Together, these data indicate that human iPS cells can be induced into mu opioid receptor- and kappa opioid receptor-expressing neurons, and that they may be useful to simulate human opioid receptor function in vitro and explore the underlying mechanisms of human conditions.
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Affiliation(s)
- Zhi-Hai Ju
- Department of Anesthesiology, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Xuan Liang
- Department of Anesthesiology, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Yao-Yao Ren
- Department of Anesthesiology, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Luo-Wa Shu
- Department of Anesthesiology, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Yan-Hong Yan
- Department of Anesthesiology, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Xu Cui
- Department of Anesthesiology, Beijing Tongren Hospital, Capital Medical University, Beijing, China
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12
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Oberhauser L, Stoeber M. Biosensors Monitor Ligand-Selective Effects at Kappa Opioid Receptors. Handb Exp Pharmacol 2021; 271:65-82. [PMID: 33387066 DOI: 10.1007/164_2020_427] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The kappa opioid receptor (KOR) has emerged as a promising therapeutic target for pain and itch treatment. There is growing interest in biased agonists that preferentially activate select signaling pathways downstream of KOR activation on the cellular level due to their therapeutic promise in retaining the analgesic and antipruritic effects and eliminating the sedative and dysphoric effects of KOR signaling on the physiological level. The concept of ligand-selective signaling includes that biased ligands promote KOR to selectively recruit one transducer or regulator protein over another, introducing bias into the signaling cascade at the very receptor-proximal level. Measuring agonist effects directly at the receptor has remained challenging and previous studies have focused on inferring agonist-selective KOR engagement with G protein relative to β-arrestin based on downstream signaling readouts. Here we discuss novel strategies to directly assess ligand-selective effects on receptor activation using KOR-interacting biosensors. The conformation-specific cytoplasmic biosensors are disconnected from the endogenous signaling machinery and provide a direct receptor-proxy readout of ligand effects in living cells. Receptor-biosensor interaction is ligand concentration dependent and can be used to determine relative ligand potency and efficacy. In addition, the biosensors reveal the existence of two dimensions of agonist bias in the cellular context: Firstly, agonists can selectively produce discrete protein-engaged KOR states and secondly, agonists can differ in the precise subcellular location at which they activate KOR. We discuss the value and the limitations of using orthogonal receptor-interacting biosensors in the quest to understand functional selectivity amongst KOR agonists in the cellular context.
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Affiliation(s)
- Lucie Oberhauser
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Miriam Stoeber
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, Geneva, Switzerland.
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13
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Abstract
Preclinical models that assess "pain" in rodents typically measure increases in behaviors produced by a "pain stimulus." A large literature exists showing that kappa opioid receptor (KOR) agonists can decrease these "pain-stimulated behaviors" following many different pain stimuli. Despite showing apparent antinociceptive properties in these preclinical models, KOR agonists failed as analgesics in clinical trials. Recent studies that assessed decreases in behavior due to a pain stimulus show that KOR agonists are not effective in restoring these "pain-depressed behaviors" to normal levels, which agrees with the lack of effectiveness for KOR agonists in clinical trials. One current explanation for the failure of previous KOR agonists in clinical trials is that those agonists activated beta-arrestin signaling and that KOR agonists with a greater bias for G protein signaling will be more successful. However, neither G protein-biased agonists nor beta-arrestin-biased agonists are very effective in assays of pain-depressed behavior, which suggests that novel biased agonists may still not be effective analgesics. This review provides a concise account of the effectiveness of KOR agonists in preclinical models of pain-stimulated and pain-depressed behaviors following the administration of different pain stimuli. Based on the previous results, it may be appropriate to include both behaviors when testing the analgesic potential of KOR agonists.
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Affiliation(s)
- Matthew F Lazenka
- Department of Biology and Chemistry, Liberty University, Lynchburg, VA, USA.
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14
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Camacho E, Marie N, Dupas Q, Martel C, Nowoczyn M, Elie N, Rochais C, Töth G, Allouche S. Impact of T161, Y318 and S363 alanine mutations on regulation of the human delta-opioid receptor (hDOPr) induced by peptidic and alkaloid agonists. Neuropharmacology 2020; 179:108286. [PMID: 32841607 DOI: 10.1016/j.neuropharm.2020.108286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Revised: 08/07/2020] [Accepted: 08/18/2020] [Indexed: 11/16/2022]
Abstract
Previously, we showed a differential regulation of the human delta-opioid receptor (hDOPr) by etorphine and [D-Pen2, D-Pen5] enkephalin (DPDPE). To understand the molecular basis of such differences, we introduced 3 alanine mutations at the residues T161. Y318 and S363. Both wild type (WT) and hDOPr mutants were expressed in HEK cells containing endogenous arrestins or CFP-tagged arrestin 3, then desensitization, internalization, recycling and phosphorylation were studied. In a context of endogenous arrestin expression, a major difference in DOPr desensitization was observed between agonists that was modified with the T161A mutation upon etorphine and with the S363A substitution upon DPDPE exposure. While both agonists induced a major receptor internalization, T161A and S363A impaired DOPr sequestration only for etorphine. However, similar level of S363 phosphorylation was measured between agonists. When CFP-tagged arrestin 3 was over-expressed, a similar profile of desensitization was measured for both agonists. In this context, all the 3 alanine mutations decreased etorphine-induced receptor desensitization. Using FRET, we showed similar interactions between WT hDOPr and arrestin 3 under DPDPE and etorphine stimulation which were delayed by both the Y318A and the S363A substitutions for etorphine. Finally, hDOPr recycling was qualitatively evaluated by microscopy and showed neither arrestin 3/hDOPr colocalization nor major impact of alanine mutations except for the S363A which impaired internalization and recycling for etorphine. The T161, Y318 and S363 residues of hDOPr could underlie the differential regulation promoted by DPDPE and etorphine.
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Affiliation(s)
- Elise Camacho
- Laboratoire de Signalisation, électrophysiologie et Imagerie des Lésions D'ischémie-reperfusion Myocardique, Normandie Univ, UNICAEN, Caen, France
| | - Nicolas Marie
- Centre National de Recherche Scientifique, Unité Mixte de Recherche 8206, Institut National de La Santé et de La Recherche Médicale. U705, Université Paris Descartes, Laboratoire de Neuropsychopharmacologie des Addictions, 4 Avenue de L'observatoire, 75006, Paris, France
| | - Quentin Dupas
- Laboratoire de Signalisation, électrophysiologie et Imagerie des Lésions D'ischémie-reperfusion Myocardique, Normandie Univ, UNICAEN, Caen, France
| | - Caroline Martel
- Laboratoire de Signalisation, électrophysiologie et Imagerie des Lésions D'ischémie-reperfusion Myocardique, Normandie Univ, UNICAEN, Caen, France
| | - Marie Nowoczyn
- Laboratoire de Signalisation, électrophysiologie et Imagerie des Lésions D'ischémie-reperfusion Myocardique, Normandie Univ, UNICAEN, Caen, France
| | - Nicolas Elie
- Plateau D'Histo-Imagerie Quantitative, CmaBio(3), SF 4206 ICORE, Normandie Univ, Caen, France
| | - Christophe Rochais
- Centre D'Etudes et de Recherche sur le Médicament de Normandie (CERMN), Normandie Univ, UNICAEN, 14000, Caen, France
| | - Geza Töth
- Biological Research Centre, Institute of Biochemistry, Hungarian Academy of Sciences, Szeged, Hungary
| | - Stéphane Allouche
- Laboratoire de Signalisation, électrophysiologie et Imagerie des Lésions D'ischémie-reperfusion Myocardique, Normandie Univ, UNICAEN, Caen, France.
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15
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Cao D, Huang P, Chiu YT, Chen C, Wang H, Li M, Zheng Y, Ehlert FJ, Zhang Y, Liu-Chen LY. Comparison of Pharmacological Properties between the Kappa Opioid Receptor Agonist Nalfurafine and 42B, Its 3-Dehydroxy Analogue: Disconnect between in Vitro Agonist Bias and in Vivo Pharmacological Effects. ACS Chem Neurosci 2020; 11:3036-3050. [PMID: 32897695 DOI: 10.1021/acschemneuro.0c00407] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Nalfurafine, a moderately selective kappa opioid receptor (KOR) agonist, is used in Japan for treatment of itch without causing dysphoria or psychotomimesis. Here we characterized the pharmacology of compound 42B, a 3-dehydroxy analogue of nalfurafine and compared with that of nalfurafine. Nalfurafine and 42B acted as full KOR agonists and partial μ opioid receptor (MOR) agonists, but 42B showed much lower potency for both receptors and lower KOR/MOR selectivity, different from previous reports. Molecular modeling revealed that water-mediated hydrogen-bond formation between 3-OH of nalfurafine and KOR accounted for its higher KOR potency than 42B. The higher potency of both at KOR over MOR may be due to hydrogen-bond formation between nonconserved Y7.35 of KOR and their carbonyl groups. Both showed modest G protein signaling biases. In mice, like nalfurafine, 42B produced antinociceptive and antiscratch effects and did not cause conditioned place aversion (CPA) in the effective dose ranges. Unlike nalfurafine, 42B caused motor incoordination and hypolocomotion. As both agonists showed G protein biases, yet produced different effects on locomotor activity and motor incoordination, the findings and those in the literature suggest caution in correlating in vitro biochemical data with in vivo behavior effects. The factors contributing to the disconnect, including pharmacodynamic and pharmacokinetic issues, are discussed. In addition, our results suggest that among the KOR-induced adverse behaviors, CPA can be separated from motor incoordination and hypolocomotion.
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Affiliation(s)
- Danni Cao
- Center for Substance Abuse Research, Temple University Lewis Katz School of Medicine, Philadelphia, Pennsylvania 19140, United States
- Beijing Key Laboratory of Neuropsychopharmacology, State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology, Beijing, 100850, China
| | - Peng Huang
- Center for Substance Abuse Research, Temple University Lewis Katz School of Medicine, Philadelphia, Pennsylvania 19140, United States
| | - Yi-Ting Chiu
- Center for Substance Abuse Research, Temple University Lewis Katz School of Medicine, Philadelphia, Pennsylvania 19140, United States
| | - Chongguang Chen
- Center for Substance Abuse Research, Temple University Lewis Katz School of Medicine, Philadelphia, Pennsylvania 19140, United States
| | - Huiqun Wang
- Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, Richmond, Virginia 23298, United States
| | - Mengchu Li
- Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, Richmond, Virginia 23298, United States
| | - Yi Zheng
- Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, Richmond, Virginia 23298, United States
| | - Frederick J. Ehlert
- Department of Pharmaceutical Sciences, Center of Health Sciences, University of California, Irvine, California 92697, United States
| | - Yan Zhang
- Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, Richmond, Virginia 23298, United States
| | - Lee-Yuan Liu-Chen
- Center for Substance Abuse Research, Temple University Lewis Katz School of Medicine, Philadelphia, Pennsylvania 19140, United States
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16
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Paton KF, Atigari DV, Kaska S, Prisinzano T, Kivell BM. Strategies for Developing κ Opioid Receptor Agonists for the Treatment of Pain with Fewer Side Effects. J Pharmacol Exp Ther 2020; 375:332-348. [PMID: 32913006 DOI: 10.1124/jpet.120.000134] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Accepted: 08/27/2020] [Indexed: 12/21/2022] Open
Abstract
There is significant need to find effective, nonaddictive pain medications. κ Opioid receptor (KOPr) agonists have been studied for decades but have recently received increased attention because of their analgesic effects and lack of abuse potential. However, a range of side effects have limited the clinical development of these drugs. There are several strategies currently used to develop safer and more effective KOPr agonists. These strategies include identifying G-protein-biased agonists, developing peripherally restricted KOPr agonists without centrally mediated side effects, and developing mixed opioid agonists, which target multiple receptors at specific ratios to balance side-effect profiles and reduce tolerance. Here, we review the latest developments in research related to KOPr agonists for the treatment of pain. SIGNIFICANCE STATEMENT: This review discusses strategies for developing safer κ opioid receptor (KOPr) agonists with therapeutic potential for the treatment of pain. Although one strategy is to modify selective KOPr agonists to create peripherally restricted or G-protein-biased structures, another approach is to combine KOPr agonists with μ, δ, or nociceptin opioid receptor activation to obtain mixed opioid receptor agonists, therefore negating the adverse effects and retaining the therapeutic effect.
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Affiliation(s)
- Kelly F Paton
- School of Biological Sciences, Centre for Biodiscovery, Victoria University of Wellington, Wellington, New Zealand (K.P., D.V.A., B.M.K.) and Department of Pharmaceutical Sciences, University of Kentucky, Lexington, Kentucky (S.K., T.P.)
| | - Diana V Atigari
- School of Biological Sciences, Centre for Biodiscovery, Victoria University of Wellington, Wellington, New Zealand (K.P., D.V.A., B.M.K.) and Department of Pharmaceutical Sciences, University of Kentucky, Lexington, Kentucky (S.K., T.P.)
| | - Sophia Kaska
- School of Biological Sciences, Centre for Biodiscovery, Victoria University of Wellington, Wellington, New Zealand (K.P., D.V.A., B.M.K.) and Department of Pharmaceutical Sciences, University of Kentucky, Lexington, Kentucky (S.K., T.P.)
| | - Thomas Prisinzano
- School of Biological Sciences, Centre for Biodiscovery, Victoria University of Wellington, Wellington, New Zealand (K.P., D.V.A., B.M.K.) and Department of Pharmaceutical Sciences, University of Kentucky, Lexington, Kentucky (S.K., T.P.)
| | - Bronwyn M Kivell
- School of Biological Sciences, Centre for Biodiscovery, Victoria University of Wellington, Wellington, New Zealand (K.P., D.V.A., B.M.K.) and Department of Pharmaceutical Sciences, University of Kentucky, Lexington, Kentucky (S.K., T.P.)
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17
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Paton KF, Biggerstaff A, Kaska S, Crowley RS, La Flamme AC, Prisinzano TE, Kivell BM. Evaluation of Biased and Balanced Salvinorin A Analogs in Preclinical Models of Pain. Front Neurosci 2020; 14:765. [PMID: 32792903 PMCID: PMC7385413 DOI: 10.3389/fnins.2020.00765] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2020] [Accepted: 06/29/2020] [Indexed: 01/09/2023] Open
Abstract
In the search for safer, non-addictive analgesics, kappa opioid receptor (KOPr) agonists are a potential target, as unlike mu-opioid analgesics, they do not have abuse potential. Salvinorin A (SalA) is a potent and selective KOPr agonist, however, clinical utility is limited by the short duration of action and aversive side effects. Biasing KOPr signaling toward G-protein activation has been highlighted as a key cellular mechanism to reduce the side effects of KOPr agonists. The present study investigated KOPr signaling bias and the acute antinociceptive effects and side effects of two novel analogs of SalA, 16-Bromo SalA and 16-Ethynyl SalA. 16-Bromo SalA showed G-protein signaling bias, whereas 16-Ethynyl SalA displayed balanced signaling properties. In the dose-response tail-withdrawal assay, SalA, 16-Ethynyl SalA and 16-Bromo SalA were more potent than the traditional KOPr agonist U50,488, and 16-Ethynyl SalA was more efficacious. 16-Ethynyl SalA and 16-Bromo SalA both had a longer duration of action in the warm water tail-withdrawal assay, and 16-Ethynyl had greater antinociceptive effect in the hot-plate assay, compared to SalA. In the intraplantar 2% formaldehyde test, 16-Ethynyl SalA and 16-Bromo SalA significantly reduced both nociceptive and inflammatory pain-related behaviors. Moreover, 16-Ethynyl SalA and 16-Bromo SalA had no anxiogenic effects in the marble burying task, and 16-Bromo SalA did not alter behavior in the elevated zero maze. Overall, 16-Ethynyl SalA significantly attenuated acute pain-related behaviors in multiple preclinical models, while the biased KOPr agonist, 16-Bromo SalA, displayed modest antinociceptive effects, and lacked anxiogenic effects.
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Affiliation(s)
- Kelly F Paton
- School of Biological Sciences, Centre for Biodiscovery, Faculty of Science, Victoria University of Wellington, Wellington, New Zealand
| | - Andrew Biggerstaff
- School of Biological Sciences, Centre for Biodiscovery, Faculty of Science, Victoria University of Wellington, Wellington, New Zealand
| | - Sophia Kaska
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY, United States
| | - Rachel S Crowley
- Department of Medicinal Chemistry, School of Pharmacy, The University of Kansas, Lawrence, KS, United States
| | - Anne C La Flamme
- School of Biological Sciences, Centre for Biodiscovery, Faculty of Science, Victoria University of Wellington, Wellington, New Zealand.,Malaghan Institute of Medical Research, Wellington, New Zealand
| | - Thomas E Prisinzano
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY, United States.,Department of Medicinal Chemistry, School of Pharmacy, The University of Kansas, Lawrence, KS, United States
| | - Bronwyn M Kivell
- School of Biological Sciences, Centre for Biodiscovery, Faculty of Science, Victoria University of Wellington, Wellington, New Zealand
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18
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Stoeber M, Jullié D, Li J, Chakraborty S, Majumdar S, Lambert NA, Manglik A, von Zastrow M. Agonist-selective recruitment of engineered protein probes and of GRK2 by opioid receptors in living cells. eLife 2020; 9:54208. [PMID: 32096468 PMCID: PMC7041944 DOI: 10.7554/elife.54208] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Accepted: 01/29/2020] [Indexed: 12/21/2022] Open
Abstract
G protein-coupled receptors (GPCRs) signal through allostery, and it is increasingly clear that chemically distinct agonists can produce different receptor-based effects. It has been proposed that agonists selectively promote receptors to recruit one cellular interacting partner over another, introducing allosteric ‘bias’ into the signaling system. However, the underlying hypothesis - that different agonists drive GPCRs to engage different cytoplasmic proteins in living cells - remains untested due to the complexity of readouts through which receptor-proximal interactions are typically inferred. We describe a cell-based assay to overcome this challenge, based on GPCR-interacting biosensors that are disconnected from endogenous transduction mechanisms. Focusing on opioid receptors, we directly demonstrate differences between biosensor recruitment produced by chemically distinct opioid ligands in living cells. We then show that selective recruitment applies to GRK2, a biologically relevant GPCR regulator, through discrete interactions of GRK2 with receptors or with G protein beta-gamma subunits which are differentially promoted by agonists. About a third of all drugs work by targeting a group of proteins known as G-protein coupled receptors, or GPCRs for short. These receptors are found on the surface of cells and transmit messages across the cell’s outer barrier. When a signaling molecule, like a hormone, is released in the body, it binds to a GPCR and changes the receptor’s shape. The change in structure affects how the GPCR interacts and binds to other proteins on the inside of the cell, triggering a series of reactions that alter the cell’s activity. Scientists have previously seen that a GPCR can trigger different responses depending on which signaling molecule is binding on the surface of the cell. However, the mechanism for this is unknown. One hypothesis is that different signaling molecules change the GPCR’s preference for binding to different proteins on the inside of the cell. The challenge has been to observe this happening without interfering with the process. Stoeber et al. have now tested this idea by attaching fluorescent tags to proteins that bind to activated GPCRs directly and without binding other signaling proteins. This meant these proteins could be tracked under a microscope as they made their way to bind to the GPCRs. Stoeber et al. focused on one particular GPCR, known as the opioid receptor, and tested the binding of two different opioid signaling molecules, etorphine and Dynorphin A. The experiments revealed that the different opioids did affect which of the engineered proteins would preferentially bind to the opioid receptor. This was followed by a similar experiment, where the engineered proteins were replaced with another protein called GRK2, which binds to the opioid receptor under normal conditions in the cell. This showed that GRK2 binds much more strongly to the opioid receptor when Dynorphin A is added compared to adding etorphine. These findings show that GPCRs can not only communicate that a signaling molecule is binding but can respond differently to convey what molecule it is more specifically. This could be important in developing drugs, particularly to specifically trigger the desired response and reduce side effects. Stoeber et al. suggest that an important next step for research is to understand how the GPCRs preferentially bind to different proteins.
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Affiliation(s)
- Miriam Stoeber
- Department of Psychiatry, University of California, San Francisco, San Francisco, United States.,Department of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland
| | - Damien Jullié
- Department of Psychiatry, University of California, San Francisco, San Francisco, United States.,Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, United States
| | - Joy Li
- Department of Psychiatry, University of California, San Francisco, San Francisco, United States.,Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, United States
| | - Soumen Chakraborty
- Center for Clinical Pharmacology, Washington University School of Medicine, St. Louis, United States.,St Louis College of Pharmacy, St. Louis, United States
| | - Susruta Majumdar
- Center for Clinical Pharmacology, Washington University School of Medicine, St. Louis, United States.,St Louis College of Pharmacy, St. Louis, United States
| | - Nevin A Lambert
- Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, Augusta, United States
| | - Aashish Manglik
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, United States.,Department of Anesthesia, University of California, San Francisco, San Francisco, United States
| | - Mark von Zastrow
- Department of Psychiatry, University of California, San Francisco, San Francisco, United States.,Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, United States
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19
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Dunn AD, Reed B, Erazo J, Ben-Ezra A, Kreek MJ. Signaling Properties of Structurally Diverse Kappa Opioid Receptor Ligands: Toward in Vitro Models of in Vivo Responses. ACS Chem Neurosci 2019; 10:3590-3600. [PMID: 31313902 DOI: 10.1021/acschemneuro.9b00195] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Biased ligands preferentially activate certain signaling pathways downstream of their target receptor, leading to differential physiological or behavioral responses downstream. The kappa opioid receptor (KOR) is a drug target for diseases involving mood and reward, such as depression and addiction. Biased KOR ligands offer the potential to overcome negative side effects that have previously hampered the therapeutic development of KOR agonists by preferentially activating certain signaling pathways. Understanding relationships between ligand bias and behavior is difficult, however, because differences in cellular context and bias quantification methods lead to variation between studies. Here, a set of 21 structurally diverse KOR ligands were tested in parallel, to systematically quantify ligand bias at the KOR. Compounds included the endogenous peptide ligand Dynorphin A(1-17), two novel compounds synthesized for our research, and 18 additional compounds of different structural classes, including morphinans and the natural product Salvinorin A. Compounds were tested for their activity in early KOR signaling pathways (G-protein and β-arrestin recruitment) in KOR-expressing U2OS cells, and ligand bias was calculated. A subset of compounds was tested for sedative properties in the rotarod assay in mice. We found that rotarod sedation significantly correlated with β-arrestin signaling in this system, indicating that this in vitro system can be used to accurately describe this in vivo behavior caused by KOR agonists. Additionally, downstream signaling pathways ERK1/2 and mTOR were evaluated, and we determined that signaling via both of these pathways could diverge from KOR-mediated G-protein and arrestin signaling in this system.
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Affiliation(s)
- Amelia D. Dunn
- Rockefeller University, 1230 York Avenue, New York, New York 10065, United States
| | - Brian Reed
- Rockefeller University, 1230 York Avenue, New York, New York 10065, United States
| | - Jose Erazo
- Rockefeller University, 1230 York Avenue, New York, New York 10065, United States
| | - Ariel Ben-Ezra
- Rockefeller University, 1230 York Avenue, New York, New York 10065, United States
| | - Mary Jeanne Kreek
- Rockefeller University, 1230 York Avenue, New York, New York 10065, United States
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20
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Kappa Opioid Receptor Agonist Mesyl Sal B Attenuates Behavioral Sensitization to Cocaine with Fewer Aversive Side-Effects than Salvinorin A in Rodents. Molecules 2018; 23:molecules23102602. [PMID: 30314288 PMCID: PMC6222496 DOI: 10.3390/molecules23102602] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2018] [Revised: 10/02/2018] [Accepted: 10/09/2018] [Indexed: 01/02/2023] Open
Abstract
The acute activation of kappa opioid receptors (KOPr) produces antinociceptive and anti-cocaine effects, however, their side-effects have limited further clinical development. Mesyl Sal B is a potent and selective KOPr analogue of Salvinorin A (Sal A), a psychoactive natural product isolated from the plant Salvia divinorum. We assessed the antinociceptive, anti-cocaine, and side-effects of Mesyl Sal B. The anti-cocaine effects are evaluated in cocaine-induced hyperactivity and behavioral sensitization to cocaine in male Sprague Dawley rats. Mesyl Sal B was assessed for anhedonia (conditioned taste aversion), aversion (conditioned place aversion), pro-depressive effects (forced swim test), anxiety (elevated plus maze) and learning and memory deficits (novel object recognition). In male B6.SJL mice, the antinociceptive effects were evaluated in warm-water (50 °C) tail withdrawal and intraplantar formaldehyde (2%) assays and the sedative effects measured with the rotarod performance task. Mesyl Sal B (0.3 mg/kg) attenuated cocaine-induced hyperactivity and behavioral sensitization to cocaine without modulating sucrose self-administration and without producing aversion, sedation, anxiety, or learning and memory impairment in rats. However, increased immobility was observed in the forced swim test indicating pro-depressive effects. Mesyl Sal B was not as potent as Sal A at reducing pain in the antinociceptive assays. In conclusion, Mesyl Sal B possesses anti-cocaine effects, is longer acting in vivo and has fewer side-effects when compared to Sal A, however, the antinociceptive effects are limited.
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21
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Roach JJ, Shenvi RA. A review of salvinorin analogs and their kappa-opioid receptor activity. Bioorg Med Chem Lett 2018; 28:1436-1445. [PMID: 29615341 PMCID: PMC5912166 DOI: 10.1016/j.bmcl.2018.03.029] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 03/09/2018] [Accepted: 03/12/2018] [Indexed: 12/23/2022]
Abstract
The plant metabolite salvinorin A potently and selectively agonizes the human kappa-opioid receptor, an emerging target for next-generation analgesics. Here we review analogs of the salvinorin chemotype and their effects on selectivity, affinity and potency. Extensive peripheral modifications using isolated salvinorin A have delivered a trove of SAR information. More deep-seated changes are now possible by advances in chemical synthesis.
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Affiliation(s)
- Jeremy J Roach
- Department of Chemistry, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Ryan A Shenvi
- Department of Chemistry, The Scripps Research Institute, La Jolla, CA 92037, USA.
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22
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Lazenka ML, Moerke MJ, Townsend EA, Freeman KB, Carroll FI, Negus SS. Dissociable effects of the kappa opioid receptor agonist nalfurafine on pain/itch-stimulated and pain/itch-depressed behaviors in male rats. Psychopharmacology (Berl) 2018; 235:203-213. [PMID: 29063139 PMCID: PMC5750069 DOI: 10.1007/s00213-017-4758-7] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Accepted: 10/03/2017] [Indexed: 12/18/2022]
Abstract
RATIONALE Nalfurafine is a G protein signaling-biased kappa opioid receptor (KOR) agonist approved in Japan for second-line treatment of uremic pruritus. Neither nalfurafine nor any other KOR agonist is currently approved anywhere for treatment of pain, but recent evidence suggests that G protein signaling-biased KOR agonists may have promise as candidate analgesics/antipruritics with reduced side effects compared to nonbiased or ß-arrestin-signaling-biased KOR agonists. OBJECTIVES This study compared nalfurafine effects in rats using assays of pain-stimulated and pain-depressed behavior used previously to evaluate other candidate analgesics. Nalfurafine effects were also examined in complementary assays of itch-stimulated and itch-depressed behavior. METHODS Intraperitoneal lactic acid (IP acid) and intradermal serotonin (ID 5HT) served as noxious and pruritic stimuli, respectively, in male Sprague Dawley rats to stimulate stretching (IP acid) or scratching (ID 5HT) or to depress positively reinforced operant responding in an assay of intracranial self-stimulation (ICSS; both stimuli). RESULTS Nalfurafine was equipotent to decrease IP acid-stimulated stretching and ID 5HT-stimulated scratching; however, doses of nalfurafine that decreased these pain/itch-stimulated behaviors also decreased control ICSS performance. Moreover, nalfurafine failed to alleviate either IP acid- or ID 5HT-induced depression of ICSS. CONCLUSIONS These results suggest that nalfurafine-induced decreases in pain/itch-stimulated behaviors may reflect nonselective decreases in motivated behavior rather than analgesia or antipruritus against the noxious and pruritic stimuli used here. This conclusion agrees with the absence of clinical data for nalfurafine analgesia and the weak clinical data for nalfurafine antipruritus. Nalfurafine bias for G protein signaling may not be sufficient for clinically safe and reliable analgesia or antipruritus.
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Affiliation(s)
- Matthew L Lazenka
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA, 23298, USA
| | - Megan J Moerke
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA, 23298, USA
| | - E Andrew Townsend
- Division of Neurobiology and Behavior Research, Department of Psychiatry and Human Behavior, University of Mississippi Medical Center, Jackson, MS, USA
| | - Kevin B Freeman
- Division of Neurobiology and Behavior Research, Department of Psychiatry and Human Behavior, University of Mississippi Medical Center, Jackson, MS, USA
| | - F Ivy Carroll
- Center for Organic and Medicinal Chemistry, Research Triangle Institute, Research Triangle Park, NC, USA
| | - S Stevens Negus
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA, 23298, USA.
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23
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The C-2 derivatives of salvinorin A, ethoxymethyl ether Sal B and β-tetrahydropyran Sal B, have anti-cocaine properties with minimal side effects. Psychopharmacology (Berl) 2017; 234:2499-2514. [PMID: 28536865 PMCID: PMC5542847 DOI: 10.1007/s00213-017-4637-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Accepted: 05/05/2017] [Indexed: 12/11/2022]
Abstract
RATIONALE Kappa-opioid receptor (KOPr) agonists have pre-clinical anti-cocaine and analgesic effects. However, side effects including sedation, dysphoria, aversion, anxiety and depression limit their therapeutic development. The unique structure of salvinorin A has been used to develop longer acting KOPr agonists. OBJECTIVES We evaluate two novel C-2 analogues of salvinorin A, ethoxymethyl ether Sal B (EOM Sal B) and β-tetrahydropyran Sal B (β-THP Sal B) alongside U50,488 for their ability to modulate cocaine-induced behaviours and side effects, pre-clinically. METHODS Anti-cocaine properties of EOM Sal B were evaluated using the reinstatement model of drug seeking in self-administering rats. EOM Sal B and β-THP Sal B were evaluated for effects on cocaine-induced hyperactivity, spontaneous locomotor activity and sucrose self-administration. EOM Sal B and β-THP Sal B were evaluated for aversive, anxiogenic and depressive-like effects using conditioned place aversion (CPA), elevated plus maze (EPM) and forced swim tests (FSTs), respectively. RESULTS EOM Sal B (0.1, 0.3 mg/kg, intraperitoneally (i.p.)) dose dependently attenuated drug seeking, and EOM Sal B (0.1 mg/kg, i.p.) and β-THP Sal B (1 mg/kg, i.p.) attenuated cocaine-induced hyperactivity. No effects on locomotor activity, open arm times (EPM) or swimming behaviours (FST) were seen with EOM (0.1 or 0.3 mg/kg, i.p.) or β-THP Sal B (1 or 2 mg/kg, i.p.). However, β-THP Sal B decreased time spent in the drug-paired chamber. CONCLUSION EOM Sal B is more potent than Sal A and β-THP Sal B in reducing drug-seeking behaviour with fewer side effects. EOM Sal B showed no effects on sucrose self-administration (0.1 mg/kg), locomotor, depressive-like, aversive-like or anxiolytic effects.
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Leppert U, Gillespie A, Orphal M, Böhme K, Plum C, Nagorsen K, Berkholz J, Kreutz R, Eisenreich A. The impact of α-Lipoic acid on cell viability and expression of nephrin and ZNF580 in normal human podocytes. Eur J Pharmacol 2017; 810:1-8. [PMID: 28606850 DOI: 10.1016/j.ejphar.2017.06.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Revised: 06/07/2017] [Accepted: 06/08/2017] [Indexed: 02/04/2023]
Abstract
Human podocytes (hPC) are essential for maintaining normal kidney function and dysfunction or loss of hPC play a pivotal role in the manifestation and progression of chronic kidney diseases including diabetic nephropathy. Previously, α-Lipoic acid (α-LA), a licensed drug for treatment of diabetic neuropathy, was shown to exhibit protective effects on diabetic nephropathy in vivo. However, the effect of α-LA on hPC under non-diabetic conditions is unknown. Therefore, we analyzed the impact of α-LA on cell viability and expression of nephrin and zinc finger protein 580 (ZNF580) in normal hPC in vitro. Protein analyses were done via Western blot techniques. Cell viability was determined using a functional assay. hPC viability was dynamically modulated via α-LA stimulation in a concentration-dependent manner. This was associated with reduced nephrin and ZNF580 expression and increased nephrin phosphorylation in normal hPC. Moreover, α-LA reduced nephrin and ZNF580 protein expression via 'kappa-light-chain-enhancer' of activated B-cells (NF-κB) inhibition. These data demonstrate that low α-LA had no negative influence on hPC viability, whereas, high α-LA concentrations induced cytotoxic effects on normal hPC and reduced nephrin and ZNF580 expression via NF-κB inhibition. These data provide first novel information about potential cytotoxic effects of α-LA on hPC under non-diabetic conditions.
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Affiliation(s)
- Ulrike Leppert
- Charité-Universitätsmedizin Berlin, CC02, Institut für Physiologie, Berlin, Germany
| | - Allan Gillespie
- Charité-Universitätsmedizin Berlin, CC04, Institut für Klinische Pharmakologie und Toxikologie, Berlin, Germany
| | - Miriam Orphal
- Charité-Universitätsmedizin Berlin, CC04, Institut für Klinische Pharmakologie und Toxikologie, Berlin, Germany
| | - Karen Böhme
- Charité-Universitätsmedizin Berlin, CC04, Institut für Klinische Pharmakologie und Toxikologie, Berlin, Germany
| | - Claudia Plum
- Charité-Universitätsmedizin Berlin, CC04, Institut für Klinische Pharmakologie und Toxikologie, Berlin, Germany
| | - Kaj Nagorsen
- Charité-Universitätsmedizin Berlin, CC02, Institut für Physiologie, Berlin, Germany
| | - Janine Berkholz
- Charité-Universitätsmedizin Berlin, CC02, Institut für Physiologie, Berlin, Germany
| | - Reinhold Kreutz
- Charité-Universitätsmedizin Berlin, CC04, Institut für Klinische Pharmakologie und Toxikologie, Berlin, Germany
| | - Andreas Eisenreich
- Charité-Universitätsmedizin Berlin, CC04, Institut für Klinische Pharmakologie und Toxikologie, Berlin, Germany.
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Olson KM, Lei W, Keresztes A, LaVigne J, Streicher JM. Novel Molecular Strategies and Targets for Opioid Drug Discovery for the Treatment of Chronic Pain. THE YALE JOURNAL OF BIOLOGY AND MEDICINE 2017; 90:97-110. [PMID: 28356897 PMCID: PMC5369049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Opioid drugs like morphine and fentanyl are the gold standard for treating moderate to severe acute and chronic pain. However, opioid drug use can be limited by serious side effects, including constipation, tolerance, respiratory suppression, and addiction. For more than 100 years, we have tried to develop opioids that decrease or eliminate these liabilities, with little success. Recent advances in understanding opioid receptor signal transduction have suggested new possibilities to activate the opioid receptors to cause analgesia, while reducing or eliminating unwanted side effects. These new approaches include designing functionally selective ligands, which activate desired signaling cascades while avoiding signaling cascades that are thought to provoke side effects. It may also be possible to directly modulate downstream signaling through the use of selective activators and inhibitors. Separate from downstream signal transduction, it has also been found that when the opioid system is stimulated, various negative feedback systems are upregulated to compensate, which can drive side effects. This has led to the development of multi-functional molecules that simultaneously activate the opioid receptor while blocking various negative feedback receptor systems including cholecystokinin and neurokinin-1. Other novel approaches include targeting heterodimers of the opioid and other receptor systems which may drive side effects, and making endogenous opioid peptides druggable, which may also reduce opioid mediated side effects. Taken together, these advances in our molecular understanding provide a path forward to break the barrier in producing an opioid with reduced or eliminated side effects, especially addiction, which may provide relief for millions of patients.
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Affiliation(s)
- Keith M. Olson
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ,Department of Chemistry and Biochemistry, College of Science, University of Arizona, Tucson, AZ
| | - Wei Lei
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ
| | - Attila Keresztes
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ
| | - Justin LaVigne
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ
| | - John M. Streicher
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ,To whom all correspondence should be addressed: John M. Streicher, Ph.D., University of Arizona, College of Medicine, Department of Pharmacology, Life Sciences North 563, Box 245050, 1501 N. Campbell Ave., Tucson, AZ 85724, 520-626-7495,
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Abstract
This paper is the thirty-eighth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2015 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior, and the roles of these opioid peptides and receptors in pain and analgesia, stress and social status, tolerance and dependence, learning and memory, eating and drinking, drug abuse and alcohol, sexual activity and hormones, pregnancy, development and endocrinology, mental illness and mood, seizures and neurologic disorders, electrical-related activity and neurophysiology, general activity and locomotion, gastrointestinal, renal and hepatic functions, cardiovascular responses, respiration and thermoregulation, and immunological responses.
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Affiliation(s)
- Richard J Bodnar
- Department of Psychology and Neuropsychology Doctoral Sub-Program, Queens College, City University of New York, Flushing, NY 11367, United States.
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Modulation of serotonin transporter function by kappa-opioid receptor ligands. Neuropharmacology 2016; 113:281-292. [PMID: 27743931 DOI: 10.1016/j.neuropharm.2016.10.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Revised: 09/16/2016] [Accepted: 10/10/2016] [Indexed: 12/11/2022]
Abstract
Kappa opioid receptor (KOR) agonists produce dysphoria and psychotomimesis. While KOR agonists produce pro-depressant-like effects, KOR antagonists produce anti-depressant-like effects in rodent models. The cellular mechanisms and downstream effector(s) by which KOR ligands produce these effects are not clear. KOR agonists modulate serotonin (5-HT) transmission in the brain regions implicated in mood and motivation regulation. Presynaptic serotonin transporter (SERT) activity is critical in the modulation of synaptic 5-HT and, subsequently, in mood disorders. Detailing the molecular events of KOR-linked SERT regulation is important for examining the postulated role of this protein in mood disorders. In this study, we used heterologous expression systems and native tissue preparations to determine the cellular signaling cascades linked to KOR-mediated SERT regulation. KOR agonists U69,593 and U50,488 produced a time and concentration dependent KOR antagonist-reversible decrease in SERT function. KOR-mediated functional down-regulation of SERT is sensitive to CaMKII and Akt inhibition. The U69,593-evoked decrease in SERT activity is associated with a decreased transport Vmax, reduced SERT cell surface expression, and increased SERT phosphorylation. Furthermore, KOR activation enhanced SERT internalization and decreased SERT delivery to the membrane. These data demonstrate that KOR activation decreases 5-HT uptake by altering SERT trafficking mechanisms and phosphorylation status to reduce the functional availability of surface SERT.
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Ruan X, Hall SM, Kaye AD. Nalfurafine hydrochloride, a selective κ opioid receptor agonist, has no reinforcing effect on intravenous self-administration in rhesus monkeys. J Pharmacol Sci 2016; 132:113-114. [DOI: 10.1016/j.jphs.2016.05.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Revised: 05/20/2016] [Accepted: 05/22/2016] [Indexed: 10/21/2022] Open
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Systematic analysis of factors influencing observations of biased agonism at the mu-opioid receptor. Biochem Pharmacol 2016; 113:70-87. [PMID: 27286929 DOI: 10.1016/j.bcp.2016.05.014] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Accepted: 05/31/2016] [Indexed: 11/24/2022]
Abstract
Biased agonism describes the ability of distinct G protein-coupled receptor (GPCR) ligands to stabilise distinct receptor conformations leading to the activation of different cell signalling pathways that can deliver different physiologic outcomes. This phenomenon is having a major impact on modern drug discovery as it offers the potential to design ligands that selectively activate or inhibit the signalling pathways linked to therapeutic effects with minimal activation or blockade of signalling pathways that are linked to the development of adverse on-target effects. However, the explosion in studies of biased agonism at multiple GPCR families in recombinant cell lines has revealed a high degree of variability on descriptions of biased ligands at the same GPCR and raised the question of whether biased agonism is a fixed attribute of a ligand in all cell types. The current study addresses this question at the mu-opioid receptor (MOP). Here, we have systematically assessed the impact of differential cellular protein complement (and cellular background), signalling kinetics and receptor species on our previous descriptions of biased agonism at MOP by several opioid peptides and synthetic opioids. Our results show that all these factors need to be carefully determined and reported when considering biased agonism. Nevertheless, our studies also show that, despite changes in overall signalling profiles, ligands that previously showed distinct bias profiles at MOP retained their uniqueness across different cell backgrounds.
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Collybolide is a novel biased agonist of κ-opioid receptors with potent antipruritic activity. Proc Natl Acad Sci U S A 2016; 113:6041-6. [PMID: 27162327 DOI: 10.1073/pnas.1521825113] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Among the opioid receptors, the κ-opioid receptor (κOR) has been gaining considerable attention as a potential therapeutic target for the treatment of complex CNS disorders including depression, visceral pain, and cocaine addiction. With an interest in discovering novel ligands targeting κOR, we searched natural products for unusual scaffolds and identified collybolide (Colly), a nonnitrogenous sesquiterpene from the mushroom Collybia maculata. This compound has a furyl-δ-lactone core similar to that of Salvinorin A (Sal A), another natural product from the plant Salvia divinorum Characterization of the molecular pharmacological properties reveals that Colly, like Sal A, is a highly potent and selective κOR agonist. However, the two compounds differ in certain signaling and behavioral properties. Colly exhibits 10- to 50-fold higher potency in activating the mitogen-activated protein kinase pathway compared with Sal A. Taken with the fact that the two compounds are equipotent for inhibiting adenylyl cyclase activity, these results suggest that Colly behaves as a biased agonist of κOR. Behavioral studies also support the biased agonistic activity of Colly in that it exhibits ∼10-fold higher potency in blocking non-histamine-mediated itch compared with Sal A, and this difference is not seen in pain attenuation by these two compounds. These results represent a rare example of functional selectivity by two natural products that act on the same receptor. The biased agonistic activity, along with an easily modifiable structure compared with Sal A, makes Colly an ideal candidate for the development of novel therapeutics targeting κOR with reduced side effects.
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Determination of sites of U50,488H-promoted phosphorylation of the mouse κ opioid receptor (KOPR): disconnect between KOPR phosphorylation and internalization. Biochem J 2015; 473:497-508. [PMID: 26635353 DOI: 10.1042/bj20141471] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Accepted: 12/03/2015] [Indexed: 12/28/2022]
Abstract
Phosphorylation sites of KOPR (κ opioid receptor) following treatment with the selective agonist U50,488H {(-)(trans)-3,4-dichloro-N-methyl-N-[2-(1-pyrrolidiny)cyclo-hexyl]benzeneacetamide} were identified after affinity purification, SDS/PAGE, in-gel digestion with Glu-C and HPLC-MS/MS. Single- and double-phosphorylated peptides were identified containing phosphorylated Ser(356), Thr(357), Thr(363) and Ser(369) in the C-terminal domain. Antibodies were generated against three phosphopeptides containing pSer(356)/pThr(357), pThr(363) and pSer(369) respectively, and affinity-purified antibodies were found to be highly specific for phospho-KOPR. U50,488H markedly enhanced staining of the KOPR by pThr(363)-, pSer(369)- and pSer(356)/pThr(357)-specific antibodies in immunoblotting, which was blocked by the selective KOPR antagonist norbinaltorphimine. Ser(369) phosphorylation affected Thr(363) phosphorylation and vice versa, and Thr(363) or Ser(369) phosphorylation was important for Ser(356)/Thr(357) phosphorylation, revealing a phosphorylation hierarchy. U50,488H, but not etorphine, promoted robust KOPR internalization, although both were full agonists. U50,488H induced higher degrees of phosphorylation than etorphine at Ser(356)/Thr(357), Thr(363) and Ser(369) as determined by immunoblotting. Using SILAC (stable isotope labelling by amino acids in cell culture) and HPLC-MS/MS, we found that, compared with control (C), U50,488H (U) and etorphine (E) KOPR promoted single phosphorylation primarily at Thr(363) and Ser(369) with U/E ratios of 2.5 and 2 respectively. Both induced double phosphorylation at Thr(363)+Ser(369) and Thr(357)+Ser(369) with U/E ratios of 3.3 and 3.4 respectively. Only U50,488H induced triple phosphorylation at Ser(356)+Thr(357)+Ser(369). An unphosphorylated KOPR-(354-372) fragment containing all of the phosphorylation sites was detected with a C/E/U ratio of 1/0.7/0.4, indicating that ∼60% and ∼30% of the mouse KOPR are phosphorylated following U50,488H and etorphine respectively. Thus KOPR internalization requires receptor phosphorylation above a certain threshold, and higher-order KOPR phosphorylation may be disproportionally important.
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