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Coutens B, Ingram SL. Key differences in regulation of opioid receptors localized to presynaptic terminals compared to somas: Relevance for novel therapeutics. Neuropharmacology 2023; 226:109408. [PMID: 36584882 PMCID: PMC9898207 DOI: 10.1016/j.neuropharm.2022.109408] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Revised: 12/05/2022] [Accepted: 12/27/2022] [Indexed: 12/29/2022]
Abstract
Opioid receptors are G protein-coupled receptors (GPCRs) that regulate activity within peripheral, subcortical and cortical circuits involved in pain, reward, and aversion processing. Opioid receptors are expressed in both presynaptic terminals where they inhibit neurotransmitter release and postsynaptic locations where they act to hyperpolarize neurons and reduce activity. Agonist activation of postsynaptic receptors at the plasma membrane signal via ion channels or cytoplasmic second messengers. Agonist binding initiates regulatory processes that include phosphorylation by G protein receptor kinases (GRKs) and recruitment of beta-arrestins that desensitize and internalize the receptors. Opioid receptors also couple to effectors from endosomes activating intracellular enzymes and kinases. In contrast to postsynaptic opioid receptors, receptors localized to presynaptic terminals are resistant to desensitization such that there is no loss of signaling in the continuous presence of opioids over the same time scale. Thus, the balance of opioid signaling in circuits expressing pre- and postsynaptic opioid receptors is shifted toward inhibition of presynaptic neurotransmitter release during continuous opioid exposure. The functional implication of this shift is not often acknowledged in behavioral studies. This review covers what is currently understood about regulation of opioid/nociceptin receptors, with an emphasis on opioid receptor signaling in pain and reward circuits. Importantly, the review covers regulation of presynaptic receptors and the critical gaps in understanding this area, as well as the opportunities to further understand opioid signaling in brain circuits. This article is part of the Special Issue on "Opioid-induced changes in addiction and pain circuits".
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Affiliation(s)
- Basile Coutens
- Department of Anesthesiology, University of Colorado Anschutz Medical Campus, Aurora, CO, 80045, USA
| | - Susan L Ingram
- Department of Anesthesiology, University of Colorado Anschutz Medical Campus, Aurora, CO, 80045, USA.
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2
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Talmont F, Veneziano R, Dietrich G, Moulédous L, Mollereau C, Zajac JM. Pharmacological insight into the activation of the human neuropeptide FF2 receptor. Peptides 2020; 134:170406. [PMID: 32920044 DOI: 10.1016/j.peptides.2020.170406] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Revised: 08/13/2020] [Accepted: 09/08/2020] [Indexed: 01/14/2023]
Abstract
The neuropeptide FF2 (NPFF2) receptor, predominantly expressed in the central nervous system, plays an important role in the modulation of sensory input and opioid analgesia, as well as in locomotion, feeding, intestinal motility, reward, and the control of obesity. The NPFF2 receptor belongs to the RFamide peptide receptor family and to the G protein coupled receptor (GPCR) super family, but contrary to many other class A GPCRs, no 3D structure has been solved. Thus, it is essential to perform mutagenesis to gain information on the fine functioning of the NPFF2 receptor. In this study, we examined the role of aspartic acid (D) from the "D/ERY/F" motif found in the second intracellular loop (ICL2) and the role of the C-terminal end of the receptor in ligand binding and signal transduction. We found that mutation D3.49A does not impair binding capacities but inhibits G protein activation as well as adenylyl cyclase regulation. Truncation of the C terminal part of the receptor has different effects depending on the position of truncation. When truncation was realized downstream of the putative acylation site, ligand binding and signal transduction capabilities were not lost, contrary to total deletion of the C terminus, which totally impairs the activity of the receptor.
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Affiliation(s)
- Franck Talmont
- CNRS, IPBS (Institut De Pharmacologie Et De Biologie Structurale) 205 Route De Narbonne, 31077 Toulouse, Cedex 4, France; Université Paul Sabatier Toulouse III, F-31300 Toulouse, France.
| | - Remi Veneziano
- CNRS, IPBS (Institut De Pharmacologie Et De Biologie Structurale) 205 Route De Narbonne, 31077 Toulouse, Cedex 4, France; Université Paul Sabatier Toulouse III, F-31300 Toulouse, France
| | - Gilles Dietrich
- INSERM IRSD (Institut De Recherche En Santé Digestive) U1220, CHU Purpan Place Du Docteur Baylac, CS 60039 31024, Toulouse Cedex 3, France
| | - Lionel Moulédous
- CNRS, IPBS (Institut De Pharmacologie Et De Biologie Structurale) 205 Route De Narbonne, 31077 Toulouse, Cedex 4, France; Université Paul Sabatier Toulouse III, F-31300 Toulouse, France
| | - Catherine Mollereau
- CNRS, IPBS (Institut De Pharmacologie Et De Biologie Structurale) 205 Route De Narbonne, 31077 Toulouse, Cedex 4, France; Université Paul Sabatier Toulouse III, F-31300 Toulouse, France
| | - Jean-Marie Zajac
- CNRS, IPBS (Institut De Pharmacologie Et De Biologie Structurale) 205 Route De Narbonne, 31077 Toulouse, Cedex 4, France; Université Paul Sabatier Toulouse III, F-31300 Toulouse, France
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3
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Han C, Lei D, Liu L, Xie S, He L, Wen S, Zhou H, Ma T, Li S. Morphine induces the differentiation of T helper cells to Th2 effector cells via the PKC-θ-GATA3 pathway. Int Immunopharmacol 2020; 80:106133. [PMID: 31931364 DOI: 10.1016/j.intimp.2019.106133] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Revised: 11/28/2019] [Accepted: 12/12/2019] [Indexed: 11/16/2022]
Abstract
BACKGROUND T help 2 (Th2) cell differentiation by morphine has been verified. However, the underlying mechanism of morphine induces Th2 cell differentiation remains elusive. The aim of the present study was to explore the possible basis of morphine induced Th2 cell differentiation. METHODS Flow cytometry analysis was used to detect the content of T help 1(Th1) cell and Th2 cell. Enzyme linked immunosorbent assay (ELISA) was performed to determine the levels of IL-4 and IFN-γ. Real-time quantitative polymerase chain reaction, electrophoretic mobility shift assay and Western blotting was conducted in this study. RESULTS Th2 cell subset and IL-4 level were elevated in morphine induced naïve T cells. Pathway determining found the protein phosphorylation level of PKC-θ and the expression and activity of the transcription factor GATA3 was also enhanced in the naïve T cells challenged by morphine. Moreover, inhibitor of morphine(naltrexone) or PKC-θ(AEB071) can reverse morphine-induced Th2 cell differentiation. CONCLUSION These results suggested that morphine induce naïve T cell differentiation to Th2 cells via the PKC-θ/GATA3 signal pathway.
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Affiliation(s)
- Chao Han
- Department of Anesthesiology, The Affiliated Yixing Hospital of Jiangsu University, Yixing, Jiangsu, China; Yixing Clinical College, Medical College of Yangzhou University, Yixing, Jiangsu, China
| | - Daoyun Lei
- Department of Anesthesiology, The Affiliated Yixing Hospital of Jiangsu University, Yixing, Jiangsu, China
| | - Li Liu
- Department of Anesthesiology, The Affiliated Yixing Hospital of Jiangsu University, Yixing, Jiangsu, China
| | - Songhui Xie
- Department of Anesthesiology, The Affiliated Yixing Hospital of Jiangsu University, Yixing, Jiangsu, China
| | - Lianping He
- School of Experience Industry, Anhui Polytechnic University, Wuhu, Anhui, China
| | - Shuang Wen
- Department of Immunology, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Hong Zhou
- Department of Immunology, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Tieliang Ma
- Department of Anesthesiology, The Affiliated Yixing Hospital of Jiangsu University, Yixing, Jiangsu, China; Yixing Clinical College, Medical College of Yangzhou University, Yixing, Jiangsu, China.
| | - Shitong Li
- Department of Anesthesiology, Shanghai General Hospital of Nanjing Medical University, Shanghai, China
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4
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Nassour H, Iddir M, Chatenet D. Towards Targeting the Urotensinergic System: Overview and Challenges. Trends Pharmacol Sci 2019; 40:725-734. [DOI: 10.1016/j.tips.2019.08.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Revised: 08/11/2019] [Accepted: 08/13/2019] [Indexed: 12/19/2022]
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5
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Trenkwalder C, Zieglgänsberger W, Ahmedzai SH, Högl B. Pain, opioids, and sleep: implications for restless legs syndrome treatment. Sleep Med 2017; 31:78-85. [DOI: 10.1016/j.sleep.2016.09.017] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Revised: 09/27/2016] [Accepted: 09/29/2016] [Indexed: 12/31/2022]
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Regan PM, Langford TD, Khalili K. Regulation and Functional Implications of Opioid Receptor Splicing in Opioid Pharmacology and HIV Pathogenesis. J Cell Physiol 2016; 231:976-85. [PMID: 26529364 PMCID: PMC4728022 DOI: 10.1002/jcp.25237] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Accepted: 11/02/2015] [Indexed: 12/18/2022]
Abstract
Despite the identification and characterization of four opioid receptor subtypes and the genes from which they are encoded, pharmacological data does not conform to the predications of a four opioid receptor model. Instead, current studies of opioid pharmacology suggest the existence of additional receptor subtypes; however, no additional opioid receptor subtype has been identified to date. It is now understood that this discrepancy is due to the generation of multiple isoforms of opioid receptor subtypes. While several mechanisms are utilized to generate these isoforms, the primary mechanism involves alternative splicing of the pre-mRNA transcript. Extensive alternative splicing patterns for opioid receptors have since been identified and discrepancies in opioid pharmacology are now partially attributed to variable expression of these isoforms. Recent studies have been successful in characterizing the localization of these isoforms as well as their specificity in ligand binding; however, the regulation of opioid receptor splicing specificity is poorly characterized. Furthermore, the functional significance of individual receptor isoforms and the extent to which opioid- and/or HIV-mediated changes in the opioid receptor isoform profile contributes to altered opioid pharmacology or the well-known physiological role of opioids in the exacerbation of HIV neurocognitive dysfunction is unknown. As such, the current review details constitutive splicing mechanisms as well as the specific architecture of opioid receptor genes, transcripts, and receptors in order to highlight the current understanding of opioid receptor isoforms, potential mechanisms of their regulation and signaling, and their functional significance in both opioid pharmacology and HIV-associated neuropathology.
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Affiliation(s)
- Patrick M. Regan
- Department of Neuroscience and Center for Neurovirology, Temple University School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - T. Dianne Langford
- Department of Neuroscience and Center for Neurovirology, Temple University School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Kamel Khalili
- Department of Neuroscience and Center for Neurovirology, Temple University School of Medicine, Philadelphia, Pennsylvania, United States of America
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7
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Regan PM, Sariyer IK, Langford TD, Datta PK, Khalili K. Morphine-induced MOR-1X and ASF/SF2 Expressions Are Independent of Transcriptional Regulation: Implications for MOR-1X Signaling. J Cell Physiol 2015; 231:1542-53. [PMID: 26553431 DOI: 10.1002/jcp.25246] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Accepted: 10/05/2015] [Indexed: 01/13/2023]
Abstract
Recently, multiple μ-opioid receptor (MOR) isoforms have been identified that originate from a single gene, OPRM1; however, both their regulation and their functional significance are poorly characterized. The objectives of this study were to decipher, first, the regulation of alternatively spliced μ-opioid receptor isoforms and the spliceosome components that determine splicing specificity and, second, the signaling pathways utilized by particular isoforms both constitutively and following agonist binding. Our studies demonstrated that the expression of a particular splice variant, MOR-1X, was up-regulated by morphine, and this coincided with an increase in the essential splicing factor ASF/SF2. Structural comparison of this isoform to the prototypical variant MOR-1 revealed that the unique distal portion of the C-terminal domain contains additional phosphorylation sites, whereas functional comparison found distinct signaling differences, particularly in the ERK and p90 RSK pathways. Additionally, MOR-1X expression significantly reduced Bax expression and mitochondrial dehydrogenase activity, suggesting a unique functional consequence for MOR-1X specific signaling. Collectively, these findings suggest that alternative splicing of the MOR is altered by exogenous opioids, such as morphine, and that individual isoforms, such as MOR-1X, mediate unique signal transduction with distinct functional consequence. Furthermore, we have identified for the first time a potential mechanism that involves the essential splicing factor ASF/SF2 through which morphine regulates splicing specificity of the MOR encoding gene, OPRM1.
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Affiliation(s)
- Patrick M Regan
- Department of Neuroscience and Center for Neurovirology, Lewis Katz School of Medicine at Temple University, Philadelphia, Pennsylvania
| | - Ilker K Sariyer
- Department of Neuroscience and Center for Neurovirology, Lewis Katz School of Medicine at Temple University, Philadelphia, Pennsylvania
| | - T Dianne Langford
- Department of Neuroscience and Center for Neurovirology, Lewis Katz School of Medicine at Temple University, Philadelphia, Pennsylvania
| | - Prasun K Datta
- Department of Neuroscience and Center for Neurovirology, Lewis Katz School of Medicine at Temple University, Philadelphia, Pennsylvania
| | - Kamel Khalili
- Department of Neuroscience and Center for Neurovirology, Lewis Katz School of Medicine at Temple University, Philadelphia, Pennsylvania
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Li Z, He SQ, Tseng PY, Xu Q, Tiwari V, Yang F, Shu B, Zhang T, Tang Z, Raja SN, Wang Y, Dong X, Guan Y. The inhibition of high-voltage-activated calcium current by activation of MrgC11 involves phospholipase C-dependent mechanisms. Neuroscience 2015; 300:393-403. [PMID: 26022362 DOI: 10.1016/j.neuroscience.2015.05.043] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Revised: 05/05/2015] [Accepted: 05/18/2015] [Indexed: 01/27/2023]
Abstract
High-voltage-activated (HVA) calcium channels play an important role in synaptic transmission. Activation of Mas-related G-protein-coupled receptor subtype C (MrgC; mouse MrgC11, rat homolog rMrgC) inhibits HVA calcium current (ICa) in small-diameter dorsal root ganglion (DRG) neurons, but the intracellular signaling cascade underlying MrgC agonist-induced inhibition of HVA ICa in native DRG neurons remains unclear. To address this question, we conducted patch-clamp recordings in MrgA3-eGFP-wild-type mice, in which most MrgA3-eGFP(+) DRG neurons co-express MrgC11 and can be identified for recording. We found that the inhibition of HVA ICa by JHU58 (0.001-100nM, a dipeptide, MrgC-selective agonist) was significantly reduced by pretreatment with a phospholipase C (PLC) inhibitor (U73122, 1μM), but not by its inactive analog (U73343) or vehicle. Further, in rats that had undergone spinal nerve injury, pretreatment with intrathecal U73122 nearly abolished the inhibition of mechanical hypersensitivity by intrathecal JHU58. The inhibition of HVA ICa in MrgA3-eGFP(+) neurons by JHU58 (100nM) was partially reduced by pretreatment with a Gβγ blocker (gallein, 100μM). However, applying a depolarizing prepulse and blocking the Gαi and Gαs pathways with pertussis toxin (PTX) (0.5μg/mL) and cholera toxin (CTX) (0.5μg/mL), respectively, had no effect. These findings suggest that activation of MrgC11 may inhibit HVA ICa in mouse DRG neurons through a voltage-independent mechanism that involves activation of the PLC, but not Gαi or Gαs, pathway.
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Affiliation(s)
- Z Li
- The Solomon H. Snyder Department of Neuroscience, Center for Sensory Biology, Johns Hopkins University, School of Medicine, Baltimore, MD 21205, USA
| | - S-Q He
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, School of Medicine, Baltimore, MD 21205, USA
| | - P-Y Tseng
- The Solomon H. Snyder Department of Neuroscience, Center for Sensory Biology, Johns Hopkins University, School of Medicine, Baltimore, MD 21205, USA
| | - Q Xu
- The Solomon H. Snyder Department of Neuroscience, Center for Sensory Biology, Johns Hopkins University, School of Medicine, Baltimore, MD 21205, USA
| | - V Tiwari
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, School of Medicine, Baltimore, MD 21205, USA
| | - F Yang
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, School of Medicine, Baltimore, MD 21205, USA
| | - B Shu
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, School of Medicine, Baltimore, MD 21205, USA; Department of Anesthesiology, Tongji Hospital, Tongji Medical College, Wuhan 430030, China
| | - T Zhang
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, School of Medicine, Baltimore, MD 21205, USA; Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing 100050, China
| | - Z Tang
- Nanjing University of Chinese Medicine, 138 Xianlin Road, Nanjing, Jiangsu 210023, China
| | - S N Raja
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, School of Medicine, Baltimore, MD 21205, USA
| | - Y Wang
- Department of Anesthesiology, Beijing Chaoyang Hospital, Capital Medical University, Beijing 100020, China
| | - X Dong
- The Solomon H. Snyder Department of Neuroscience, Center for Sensory Biology, Johns Hopkins University, School of Medicine, Baltimore, MD 21205, USA; Howard Hughes Medical Institute, Johns Hopkins University, School of Medicine, Baltimore, MD 21287, USA.
| | - Y Guan
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, School of Medicine, Baltimore, MD 21205, USA.
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9
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Ho J, Perez-Aguilar JM, Gao L, Saven JG, Matsunami H, Eckenhoff RG. Molecular recognition of ketamine by a subset of olfactory G protein-coupled receptors. Sci Signal 2015; 8:ra33. [PMID: 25829447 DOI: 10.1126/scisignal.2005912] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Ketamine elicits various neuropharmacological effects, including sedation, analgesia, general anesthesia, and antidepressant activity. Through an in vitro screen, we identified four mouse olfactory receptors (ORs) that responded to ketamine. In addition to their presence in the olfactory epithelium, these G protein (heterotrimeric guanine nucleotide-binding protein)-coupled receptors (GPCRs) are distributed throughout the central nervous system. To better understand the molecular basis of the interactions between ketamine and ORs, we used sequence comparison and molecular modeling to design mutations that (i) increased, reduced, or abolished ketamine responsiveness in responding receptors, and (ii) rendered nonresponding receptors responsive to ketamine. We showed that olfactory sensory neurons (OSNs) that expressed distinct ORs responded to ketamine in vivo, suggesting that ORs may serve as functional targets for ketamine. The ability to both abolish and introduce responsiveness to ketamine in GPCRs enabled us to identify and confirm distinct interaction loci in the binding site, which suggested a signature ketamine-binding pocket that may guide exploration of additional receptors for this general anesthetic drug.
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Affiliation(s)
- Jianghai Ho
- Department of Molecular Genetics and Microbiology, and Department of Neurobiology, Duke University, Durham, NC 27710, USA
| | | | - Lu Gao
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Jeffery G Saven
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Hiroaki Matsunami
- Department of Molecular Genetics and Microbiology, and Department of Neurobiology, Duke University, Durham, NC 27710, USA.,Duke Institute for Brain Sciences, Duke University, Durham, NC 27710, USA
| | - Roderic G Eckenhoff
- Department of Anesthesiology and Critical Care, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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10
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Minami K, Sudo Y, Miyano K, Murphy RS, Uezono Y. µ-Opioid receptor activation by tramadol and O-desmethyltramadol (M1). J Anesth 2014; 29:475-479. [PMID: 25394761 DOI: 10.1007/s00540-014-1946-z] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Accepted: 10/29/2014] [Indexed: 11/30/2022]
Abstract
Tramadol has been used as an analgesic for several decades. µ-Opioid receptors (µORs) are the major receptors that mediate the analgesic effects of opioids. Although µORs have been thought to be one of the sites of action of tramadol, there has been no report that directly proves whether tramadol is an agonist of μOR or not. In this study, we examined the effects of tramadol and its main active metabolite O-desmethyltramadol (M1), on the function of µORs using Xenopus oocytes expressing cloned human µORs. The effects of tramadol and M1 were evaluated using the Ca(2+)-activated Cl(-) current assay method for G(i/o)-protein-coupled receptors by using a µOR fused to G(qi5) (µOR-G(qi5)) in Xenopus oocytes. DAMGO [(D-Ala(2), N-MePhe(4), Gly(5)-ol)-enkephalin] evoked Cl(-) currents in oocytes expressing µOR-G(qi5) in a concentration-dependent manner. Tramadol and M1 also evoked Cl(-) currents in the oocytes expressing µOR-G(qi5); however, relatively higher concentrations (compared to DMAGO) were necessary to induce such currents. Tramadol and M1 had a direct effect on µORs expressed in Xenopus oocytes. Although the monoamine uptake system and several types of ligand-gated ion channels are thought to be one of the targets for tramadol, tramadol-induced antinociception may be mediated at least in part, by the direct activation of µORs.
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Affiliation(s)
- Kouichiro Minami
- Emergency Life Saving and Technique Tokyo, 4-5 Minamiosawa, Hachioji, Tokyo, 192-0364, Japan.
| | - Yuka Sudo
- Department of Molecular Pathology and Metabolic Disease, Faculty of Pharmaceutical Sciences, Tokyo University of Science, Chiba, Japan
| | - Kanako Miyano
- Division of Cancer Pathophysiology, National Cancer Center Research Institute, Tokyo, Japan
| | - Robert S Murphy
- Center of Fundamental Education, University of Kitakyushu, Fukuoka, Japan
| | - Yasuhito Uezono
- Division of Cancer Pathophysiology, National Cancer Center Research Institute, Tokyo, Japan
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Abstract
G protein-coupled receptors (GPCRs) mediate the majority of cellular responses to hormones and neurotransmitters within the human body. They have much potential in the emerging field of synthetic biology, which is the rational, systematic design of biological systems with desired functionality. The responsiveness of GPCRs to a plethora of endogenous and exogenous ligands and stimuli make them ideal sensory receptor modules of synthetic gene networks. Such networks can activate target gene expression in response to a specific stimulus. Additionally, because GPCRs are important pharmacological targets of various human diseases, genes encoding their protein/peptide ligands can also be incorporated as target genes of the response output elements of synthetic gene networks. This review aims to critically examine the potential role of GPCRs in constructing therapeutic synthetic gene networks and to discuss various challenges in utilizing GPCRs for synthetic biology applications.
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Affiliation(s)
- Boon Chin Heng
- Department of Biosystems Science and Engineering, ETH Zürich, CH-4058 Basel, Switzerland;
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12
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Perez-Aguilar JM, Xi J, Matsunaga F, Cui X, Selling B, Saven JG, Liu R. A computationally designed water-soluble variant of a G-protein-coupled receptor: the human mu opioid receptor. PLoS One 2013; 8:e66009. [PMID: 23799068 PMCID: PMC3682944 DOI: 10.1371/journal.pone.0066009] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2013] [Accepted: 04/30/2013] [Indexed: 11/19/2022] Open
Abstract
G-protein-coupled receptors (GPCRs) play essential roles in various physiological processes, and are widely targeted by pharmaceutical drugs. Despite their importance, studying GPCRs has been problematic due to difficulties in isolating large quantities of these membrane proteins in forms that retain their ligand binding capabilities. Creating water-soluble variants of GPCRs by mutating the exterior, transmembrane residues provides a potential method to overcome these difficulties. Here we present the first study involving the computational design, expression and characterization of water-soluble variant of a human GPCR, the human mu opioid receptor (MUR), which is involved in pain and addiction. An atomistic structure of the transmembrane domain was built using comparative (homology) modeling and known GPCR structures. This structure was highly similar to the subsequently determined structure of the murine receptor and was used to computationally design 53 mutations of exterior residues in the transmembrane region, yielding a variant intended to be soluble in aqueous media. The designed variant expressed in high yield in Escherichia coli and was water soluble. The variant shared structural and functionally related features with the native human MUR, including helical secondary structure and comparable affinity for the antagonist naltrexone (Kd = 65 nM). The roles of cholesterol and disulfide bonds on the stability of the receptor variant were also investigated. This study exemplifies the potential of the computational approach to produce water-soluble variants of GPCRs amenable for structural and functionally related characterization in aqueous solution.
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Affiliation(s)
- Jose Manuel Perez-Aguilar
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Jin Xi
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Felipe Matsunaga
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Xu Cui
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- Department of Anesthesiology, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Bernard Selling
- Impact Biologicals Inc., Swarthmore, Pennsylvania, United States of America
| | - Jeffery G. Saven
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- * E-mail: (RL); (JGS)
| | - Renyu Liu
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- * E-mail: (RL); (JGS)
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14
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Minami K, Uezono Y. The recent progress in research on effects of anesthetics and analgesics on G protein-coupled receptors. J Anesth 2012; 27:284-92. [PMID: 23099434 DOI: 10.1007/s00540-012-1507-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2012] [Accepted: 10/09/2012] [Indexed: 11/25/2022]
Abstract
The exact mechanisms of action behind anesthetics and analgesics are still unclear. Much attention was focused on ion channels in the central nervous system as targets for anesthetics and analgesics in the 1980s. During the 1990s, major advances were made in our understanding of the physiology and pharmacology of G protein coupled receptor (GPCR) signaling. Thus, several lines of studies have shown that G protein coupled receptors (GPCRs) are one of the targets for anesthetics and analgesics and especially, that some of them inhibit the functions of GPCRs, i.e,, muscarinic receptors and substance P receptors. However, these studies had been focused on only G(q) coupled receptors. There has been little work on G(s)- and G(i)-coupled receptors. In the last decade, a new assay system, using chimera G(i/o)-coupled receptor fused to Gq(i5), has been established and the effects of anesthetics and analgesics on the function of G(i)-coupled receptors is now more easily studied. This review highlights the recent progress of the studies regarding the effects of anesthetics and analgesics on GPCRs.
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Affiliation(s)
- Kouichiro Minami
- Cancer Pathophysiology Division, National Cancer Center Research Institute, Tokyo 104-0045, Japan.
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Perez-Aguilar JM, Saven JG, Liu R. Human μ Opioid Receptor Models with Evaluation of the Accuracy Using the Crystal Structure of the Murine μ Opioid Receptor. ACTA ACUST UNITED AC 2012; 3:218. [PMID: 24527268 PMCID: PMC3920553 DOI: 10.4172/2155-6148.1000218] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Models of the human μ opioid receptor were constructed using available G-protein-coupled receptor (GPCR) structures using homology (comparative) modeling techniques. The recent publication of a high-resolution crystal structure of a construct based on the murine μ opioid receptor offers a unique opportunity to evaluate the reliability of the homology models and test the relevance of introducing more templates (known structures) to increase the accuracy of the comparative models. In the first model two templates were used: the β2 adrenergic and bovine rhodopsin receptors. For the second model, four templates were utilized: the β2 adrenergic, bovine rhodopsin, β1 adrenergic, and A2A adenosine receptors. Including additional templates improved the accuracy of structural motifs and other features of the model when the same sequence alignment was used. The predicted structures were especially relevant in the case of important receptor regions such as the DRY motif, which has been associated with receptor activation. Additionally, this study showed that receptor sequence similarity is crucial in homology modeling, as indicated in the case of the highly diverse EC2 loop. This study demonstrates the reliability of the homology modeling technique in the case of the μ opioid receptor, a member of the rhodopsin-like family class of GPCRs. The addition of more templates improved the accuracy of the model. The findings regarding the modeling has significant implication to other GPCRs where the crystal structure is still unknown and suggest that homology modeling techniques can provide high quality structural models for interpreting experimental findings and formulating structurally based hypotheses regarding the activity of these important receptors.
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Affiliation(s)
| | - Jeffery G Saven
- Department of Chemistry, University of Pennsylvania, Philadelphia, 19104, USA
| | - Renyu Liu
- Department of Anesthesiology and Critical Care, Hospital of University of Pennsylvania, Philadelphia, 19104, USA
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Minami K, Sudo Y, Yokoyama T, Ogata J, Takeuchi M, Uezono Y. Sevoflurane inhibits the µ-opioid receptor function expressed in Xenopus oocytes. Pharmacology 2011; 88:127-32. [PMID: 21912198 DOI: 10.1159/000330096] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2011] [Accepted: 06/01/2011] [Indexed: 11/19/2022]
Abstract
Sevoflurane is widely used for anesthesia, and is commonly used together with opioids in clinical practice. However, the effects of sevoflurane on μ-opioid receptor (μOR) functions is still unclear. In this study, the effects of sevoflurane on μOR functions were analyzed by using Xenopus oocytes expressing a μOR fused to chimeric Gα protein G(qi5) (μOR-G(qi5)). Sevoflurane by itself did not elicit any currents in oocytes expressing μOR-G(qi5), whereas sevoflurane inhibited the [D-Ala(2),N-Me-Phe(4),Gly(5)-ol]-enkephalin (DAMGO)-induced Cl(-) currents at clinically used concentrations. Sevoflurane did not affect the Cl(-) currents induced by AlF(4)(-), which directly led to activation of G proteins. The inhibitory effects of sevoflurane on the DAMGO-induced currents were not observed in oocytes pretreated with the protein kinase C (PKC) inhibitor GF109203X. These findings suggest that sevoflurane would inhibit μOR function. Further, the mechanism of inhibition by sevoflurane would be mediated by PKC.
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Affiliation(s)
- Kouichiro Minami
- Department of Anesthesiology and Critical Care Medicine, Jichi Medical University, Tochigi, Japan.
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Sauriyal DS, Jaggi AS, Singh N. Extending pharmacological spectrum of opioids beyond analgesia: multifunctional aspects in different pathophysiological states. Neuropeptides 2011; 45:175-88. [PMID: 21208657 DOI: 10.1016/j.npep.2010.12.004] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/20/2010] [Revised: 12/06/2010] [Accepted: 12/07/2010] [Indexed: 11/29/2022]
Abstract
Opioids are well known to exert potent central analgesic actions. In recent years, the numerous studies have unfolded the critical role of opioids in the pathophysiology of various diseases as well as in biological phenomenon of therapeutic interest. The endogenous ligands of opioid receptors are derived from three independent genes and their appropriate processing yields the major representative opioid peptides beta-endorphin, met-enkephalin, leu-enkephalin and dynorphin, respectively. These peptides and their derivatives exhibit different affinity and selectivity for the mu-, delta- and kappa-receptors located on the central and the peripheral neurons, neuroendocrine, immune, and mucosal cells and on many other organ systems. The present review article highlights the role of these peptides in central nervous system disorders such as depression, anxiety, epilepsy, and stress; gastrointestinal disorders such as diarrhea, postoperative ileus, ulceration, and irritable bowel syndrome; immune system and related inflammatory disorders such as osteoarthritis and rheumatoid arthritis; and others including respiratory, alcoholism and obesity/binge eating. Furthermore, the key role of opioids in different forms of pre- and post-conditioning including ischemic and pharmacological along with in remote preconditioning has also been described.
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Kao JH, Chen SL, Ma HI, Law PY, Tao PL, Loh HH. Intrathecal delivery of a mutant micro-opioid receptor activated by naloxone as a possible antinociceptive paradigm. J Pharmacol Exp Ther 2010; 334:739-45. [PMID: 20554907 DOI: 10.1124/jpet.109.165399] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Direct injection of double-stranded adeno-associated virus type 2 (dsAAV2) with a mu-opioid receptor (MOR) mutant [S4.45(196)A], and a reporter protein (enhanced green fluorescent protein) into the spinal cord (S2/S3) dorsal horn region of ICR mice resulted in antinociceptive responses to systemic injection of opioid antagonist naloxone without altering the acute agonist morphine responses and no measurable tolerance or dependence development during subchronic naloxone treatment. To develop further such mutant MORs into a therapeutic agent in pain management, a less invasive method for virus delivery is needed. Thus, in current studies, the dsAAV2 was locally injected into the subarachnoid space of the spinal cord by intrathecal administration. Instead of using the MORS196A mutant, we constructed the dsAAV2 vector with the MORS196ACSTA mutant, a receptor mutant in which naloxone has been shown to exhibit full agonistic properties in vitro. After 2 weeks of virus injection, naloxone (10 mg/kg s.c.) elicited antinociceptive effect (determined by tail-flick test) without tolerance (10 mg/kg s.c., b.i.d. for 6 days) and significant withdrawal symptoms. On the other hand, subchronic treatment with morphine (10 mg/kg s.c., b.i.d.) for 6 days induced significant tolerance (4.8-fold) and withdrawal symptoms. Furthermore, we found that morphine, but not naloxone, induced the rewarding effects (determined by conditioned place preference test). These data suggest that local expression of MORS196ACSTA in spinal cord and systemic administration of naloxone has the potential to be developed into a new strategy in the management of pain without addiction liability.
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Affiliation(s)
- J H Kao
- Graduate Institute of Life Science, National Defense Medical Center, Taipei, Taiwan, Republic of China
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19
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Abstract
G protein-coupled receptors, in particular, Ca(2+)-mobilizing G(q)-coupled receptors have been reported to be targets for anesthetics. Opioids are commonly used analgesics in clinical practice, but the effects of anesthetics on the opioid mu-receptors (muOR) have not been systematically examined. We report here an electrophysiological assay to analyze the effects of anesthetics and ethanol on the functions of muOR in Xenopus oocytes expressing a muOR fused to chimeric Galpha protein G(qi5) (muOR-G(qi5)). Using this system, the effects of halothane, ketamine, propofol, and ethanol on the muOR functions were analyzed. In oocytes expressing muOR-G(qi5), the( )muOR agonist DAMGO ([D-Ala(2),N-MePhe(4),Gly-ol]-enkephalin) elicited Ca(2+)-activated Cl(-) currents in a concentration-dependent manner (EC(50) = 0.24 microM). Ketamine, propofol, halothane, and ethanol themselves did not elicit any currents in oocytes expressing muOR-G(qi5), whereas ketamine and ethanol inhibited the DAMGO-induced Cl(-) currents at clinically equivalent concentrations. Propofol and halothane inhibited the DAMGO-induced currents only at higher concentrations. These findings suggest that ketamine and ethanol may inhibit muOR functions in clinical practice. We propose that the electrophysiological assay in Xenopus oocytes expressing muOR-G(qi5) would be useful for analyzing the effects of anesthetics and analgesics on opioid receptor function.
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Affiliation(s)
- Kouichiro Minami
- Department of Anesthesiology and Critical Care Medicine, Jichi Medical University, Japan.
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Abstract
The myriad of side effects that associate with morphine has been problematic in the clinical use to manage moderate to severe pain. It has been the holy grail of the pharmacologists to develop a compound, or treatment paradigm that could retain the analgesic effect of the drug as eliminating or reducing the side effects, mainly the tolerance and addiction development associates with chronic usage of the drug. In our earlier receptor structure/activities studies, we discovered an unique mutation of a conserved Ser in the fourth transmembrane domain of the opioid receptor that the alkaloid antagonist could activate the receptor. On the basis of this initial finding, we decide to explore the possibility of using virus to deliver the mutant mu-opioid receptor at the various sites of the nociceptive pathway and induce the antinociceptive responses with the systemic administration of opioid antagonists. In this article, we will summarize the progress of such approach and the probable advantages over the conventional approach of drug development in the treatment of chronic pain.
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Affiliation(s)
- Pao-Luh Tao
- Department of Pharmacology, National Defense Medical Center, Taipei, Taiwan, Republic of China
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Marron Fdez de Velasco E, Law PY, Rodríguez RE. Mu opioid receptor from the zebrafish exhibits functional characteristics as those of mammalian mu opioid receptor. Zebrafish 2009; 6:259-68. [PMID: 19761379 DOI: 10.1089/zeb.2009.0594] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The functional characterization of the mu opioid receptor from the zebrafish (zfMOR) is reported here. After transfection in HEK-293 cell line, using both peptidergic and nonpeptidergic opioid ligands in the competition and saturation-binding experiments, in addition to the functional assays of (35)S-GTPgammaS-binding assays and intracellular 3'-5'-cyclic adenosine monophosphate (cAMP) level determinations, we demonstrate that zfMOR exhibits a pharmacological profile similar to that of the mammalian MOR. Besides, the internalization process of zfMOR after opiate agonist treatment (morphine, DAMGO, etorphine) resembles the pattern observed for its mammalian counterpart. These similarities suggest that the zebrafish is a good model for the study of the opioid effects in development.
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Affiliation(s)
- Ezequiel Marron Fdez de Velasco
- Department of Biochemistry and Molecular Biology, Institute of Neurosciences of Castilla y León, University of Salamanca, Salamanca, Spain
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Liu H, Li H, Guo L, Li M, Li C, Wang S, Jiang W, Liu X, McNutt MA, Li G. Mechanisms involved in phosphatidylinositol 3-kinase pathway mediated up-regulation of the mu opioid receptor in lymphocytes. Biochem Pharmacol 2009; 79:516-23. [PMID: 19765550 DOI: 10.1016/j.bcp.2009.09.013] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2009] [Revised: 09/08/2009] [Accepted: 09/10/2009] [Indexed: 01/12/2023]
Abstract
Despite the substantial progress made in understanding initiation expression of the MOR gene in lymphocytes, the signal pathway associated with MOR gene transcription remains to be better defined. As the phosphatidylinositol 3-kinase (PI3K)/AKT pathway can mediate diverse biological responses and is crucial for optimal immune responses and lymphocyte development, this study was undertaken to delineate the role of PI3K/AKT signaling in expression of the MOR gene in CEM x174 cells. The data show that morphine treatment enhanced the level of phosphorylated, rather than un-phosphorylated, PI3K and AKT, which were synchronously recruited to membrane. The levels of PTEN and p53 which are negative regulators of these signal molecules were reduced, and as a result, the interaction between PTEN and p53 was completely interrupted. With morphine treatment, the levels of both cytoplasmic and nuclear E2F1 which is the downstream effecter of AKT were elevated and the interaction of E2F1 with YY1, rather than Sp1, was also increased. Subsequently, E2F1 triggered the transcription of the MOR gene through its enhanced ability to bind the element in promoter region of the MOR gene. All responses to morphine were abolished by naloxone, which is an antagonist of MOR, or by LY294002, an inhibitor of PI3K, implying specific involvement of PI3K/AKT. These results strongly suggest that the PI3K/AKT pathway plays a critical role in the transfer of signal from morphine stimuli to the machinery by which MOR gene transcription is initiated.
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Affiliation(s)
- Han Liu
- Department of Biochemistry and Molecular Biology, Peking University Health Science Center, Peking University, Beijing 100083, China
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Liu X, Kai M, Jin L, Wang R. Computational study of the heterodimerization between mu and delta receptors. J Comput Aided Mol Des 2009; 23:321-32. [PMID: 19214754 DOI: 10.1007/s10822-009-9262-7] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2008] [Accepted: 01/18/2009] [Indexed: 11/27/2022]
Abstract
A growing body of evidence indicated that the G protein coupled receptors exist as homo- or hetero-dimers in the living cell. The heterodimerization between mu and delta opioid receptors has attracted researchers' particular interests, it is reported to display novel pharmacological and signalling regulation properties. In this study, we construct the full-length 3D-model of mu and delta opioid receptors using the homology modelling method. Threading program was used to predict the possible templates for the N- and C-terminus domains. Then, a 30 ns molecular dynamics simulations was performed with each receptor embedded in an explicit membrane-water environment to refine and explore the conformational space. Based on the structures extracted from the molecular dynamics, the likely interface of mu-delta heterodimer was investigated through the analysis of protein-protein docking, cluster, shape complementary and interaction energy. The computational modelling works revealed that the most likely interface of heterodimer was formed between the transmembrane1,7 (TM1,7) domains of mu receptor and the TM(4,5) domains of delta receptor, with emphasis on mu-TM1 and delta-TM4, the next likely interface was mu(TM6,7)-delta(TM4,5), with emphasis on mu-TM6 and delta-TM4. Our results were consistent with previous reports.
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Affiliation(s)
- Xin Liu
- Institute of Biochemistry and Molecular Biology, School of Basic Medical Science, State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou, China
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Smith JL, Kupchak BR, Garitaonandia I, Hoang LK, Maina AS, Regalla LM, Lyons TJ. Heterologous expression of human mPRalpha, mPRbeta and mPRgamma in yeast confirms their ability to function as membrane progesterone receptors. Steroids 2008; 73:1160-73. [PMID: 18603275 PMCID: PMC2597464 DOI: 10.1016/j.steroids.2008.05.003] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2008] [Revised: 05/06/2008] [Accepted: 05/08/2008] [Indexed: 12/15/2022]
Abstract
The nuclear progesterone receptor (nPR) mediates many of the physiological effects of progesterone by regulating the expression of genes, however, progesterone also exerts non-transcriptional (non-genomic) effects that have been proposed to rely on a receptor that is distinct from nPR. Several members of the progestin and AdipoQ-Receptor (PAQR) family were recently identified as potential mediators of these non-genomic effects. Membranes from cells expressing these proteins, called mPRalpha, mPRbeta and mPRgamma, were shown to specifically bind progesterone and have G-protein coupled receptor (GPCR) characteristics, although other studies dispute these findings. To clarify the role of these mPRs in non-genomic progesterone signaling, we established an assay for PAQR functional evaluation using heterologous expression in Saccharomyces cerevisiae. Using this assay, we demonstrate unequivocally that mPRalpha, mPRbeta and mPRgamma can sense and respond to progesterone with EC(50) values that are physiologically relevant. Agonist profiles also show that mPRalpha, mPRbeta and mPRgamma are activated by ligands, such as 17alpha-hydroxyprogesterone, that are known to activate non-genomic pathways but not nPR. These results strongly suggest that these receptors may indeed function as the long-sought-after membrane progesterone receptors. Additionally, we show that two uncharacterized PAQRs, PAQR6 and PAQR9, are also capable of responding to progesterone. These mPR-like PAQRs have been renamed as mPRdelta (PAQR6) and mPRvarepsilon (PAQR9). Additional characterization of mPRgamma and mPRalpha indicates that their progesterone-dependent signaling in yeast does not require heterotrimeric G-proteins, thus calling into question the characterization of the mPRs as a novel class of G-protein coupled receptor.
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Affiliation(s)
- Jessica L. Smith
- Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, FL 32601
| | - Brian R. Kupchak
- Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, FL 32601
| | - Ibon Garitaonandia
- Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, FL 32601
| | - L. Kim Hoang
- Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, FL 32601
| | - Andrew S. Maina
- Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, FL 32601
| | - Lisa M. Regalla
- Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, FL 32601
| | - Thomas J. Lyons
- Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, FL 32601
- Corresponding author/reprint requests, University of Florida Department of Chemistry, P.O. Box 117200 Gainesville, FL 32611, tel: 352-846-3392, fax: 352-846-2095,
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Deo SH, Barlow MA, Gonzalez L, Yoshishige D, Caffrey JL. Cholinergic location of δ-opioid receptors in canine atria and SA node. Am J Physiol Heart Circ Physiol 2008; 294:H829-38. [DOI: 10.1152/ajpheart.01141.2007] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
δ-Opioid receptors (DORs) are associated with ischemic preconditioning and vagal transmission in the sinoatrial (SA) node and atria. Although functional studies suggested that DORs are prejunctional on parasympathetic nerve terminals, their precise location remains unconfirmed. DORs were colocalized in tissue slices and synaptosomes from the canine right atrium and SA node along with cholinergic and adrenergic markers, vesicular acetylcholine transporter (VAChT), and tyrosine hydroxylase (TH). Synapsin I immunofluorescence verified the neural character of tissue structures and isolated synaptosomes. Acetylcholine and norepinephrine measurements suggested the presence of both cholinergic and adrenergic synaptosomes. Fluorescent analysis of VAChT and TH signals indicated that >80% of the synapsin-positive synaptosomes were of cholinergic origin and <8% were adrenergic. DORs colocalized 75–85% with synapsin in tissue slices from both atria and SA node. The colocalization was equally strong (85%) for nodal synaptosomes but less so for atrial synaptosomes (57%). Colocalization between DOR and VAChT was 75–85% regardless of the source. Overlap between DOR and TH was uniformly low, ranging from 8% to 17%. Western blots with synaptosomal extracts confirmed two DOR-positive bands at molecular masses corresponding to those reported for DOR monomers and dimers. The abundance of DOR was greater in nodal synaptosomes than in atrial synaptosomes, largely attributable to a greater abundance of monomers in the SA node. The abundant nodal and atrial DORs predominantly associated with cholinergic nerve terminals support the hypothesis that prejunctional DORs regulate vagal transmission locally within the heart.
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Abstract
This paper is the 28th consecutive installment of the annual review of research concerning the endogenous opioid system, now spanning over a quarter-century of research. It summarizes papers published during 2005 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 (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurologic disorders (Section 11); electrical-related activity, neurophysiology and transmitter release (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration and thermoregulation (Section 16); immunological responses (Section 17).
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Affiliation(s)
- Richard J Bodnar
- Department of Psychology and Neuropsychology Doctoral Sub-Program, Queens College, City University of New York, 65-30 Kissena Blvd., Flushing, NY 11367, USA.
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Abstract
What is a drug target? And how many such targets are there? Here, we consider the nature of drug targets, and by classifying known drug substances on the basis of the discussed principles we provide an estimation of the total number of current drug targets.
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Affiliation(s)
- Peter Imming
- Institut für Pharmazie, Martin-Luther-Universität Halle-Wittenberg, 06120 Halle, Germany.
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