1
|
van der Westhuizen ET. Single nucleotide variations encoding missense mutations in G protein-coupled receptors may contribute to autism. Br J Pharmacol 2024; 181:2158-2181. [PMID: 36787962 DOI: 10.1111/bph.16057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Revised: 12/21/2022] [Accepted: 02/04/2023] [Indexed: 02/16/2023] Open
Abstract
Autism is a neurodevelopmental condition with a range of symptoms that vary in intensity and severity from person to person. Genetic sequencing has identified thousands of genes containing mutations in autistic individuals, which may contribute to the development of autistic symptoms. Several of these genes encode G protein-coupled receptors (GPCRs), which are cell surface expressed proteins that transduce extracellular messages to the intracellular space. Mutations in GPCRs can impact their function, resulting in aberrant signalling within cells and across neurotransmitter systems in the brain. This review summarises the current knowledge on autism-associated single nucleotide variations encoding missense mutations in GPCRs and the impact of these genetic mutations on GPCR function. For some autism-associated mutations, changes in GPCR expression levels, ligand affinity, potency and efficacy have been observed. However, for many the functional consequences remain unknown. Thus, further work to characterise the functional impacts of the genetically identified mutations is required. LINKED ARTICLES: This article is part of a themed issue Therapeutic Targeting of G Protein-Coupled Receptors: hot topics from the Australasian Society of Clinical and Experimental Pharmacologists and Toxicologists 2021 Virtual Annual Scientific Meeting. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v181.14/issuetoc.
Collapse
|
2
|
Considerations on Using Antibodies for Studying the Dynorphins/Kappa Opioid Receptor System. Handb Exp Pharmacol 2022; 271:23-38. [PMID: 34085120 PMCID: PMC9125580 DOI: 10.1007/164_2021_467] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Antibodies are important tools for protein and peptide research, including for the kappa opioid receptor (KOR) and dynorphins (Dyns). Well-characterized antibodies are essential for rigorous and reproducible research. However, lack of validation of antibody specificity has been thought to contribute significantly to the reproducibility crisis in biomedical research. Since 2003, many scientific journals have required documentation of validation of antibody specificity and use of knockout mouse tissues as a negative control is strongly recommended. Lack of specificity of antibodies against many G protein-coupled receptors (GPCRs) after extensive testing has been well-documented, but antibodies generated against partial sequences of the KOR have not been similarly investigated. For the dynorphins, differential processing has been described in distinct brain areas, resulting in controversial findings in immunohistochemistry (IHC) when different antibodies were used. In this chapter, we summarized accepted approaches for validation of antibody specificity. We discussed two KOR antibodies most commonly used in IHC and described generation and characterization of KOR antibodies and phospho-KOR specific antibodies in western blotting or immunoblotting (IB). In addition, applying antibodies targeting prodynorphin or mature dynorphin A illustrates the diversity of results obtained regarding the distribution of dynorphins in distinct brain areas.
Collapse
|
3
|
Grinnell SG, Uprety R, Varadi A, Subrath J, Hunkele A, Pan YX, Pasternak GW, Majumdar S. Synthesis and Characterization of Azido Aryl Analogs of IBNtxA for Radio-Photoaffinity Labeling Opioid Receptors in Cell Lines and in Mouse Brain. Cell Mol Neurobiol 2020; 41:977-993. [PMID: 32424771 DOI: 10.1007/s10571-020-00867-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Accepted: 05/05/2020] [Indexed: 10/24/2022]
Abstract
Mu opioid receptors (MOR-1) mediate the biological actions of clinically used opioids such as morphine, oxycodone, and fentanyl. The mu opioid receptor gene, OPRM1, undergoes extensive alternative splicing, generating multiple splice variants. One type of splice variants are truncated variants containing only six transmembrane domains (6TM) that mediate the analgesic action of novel opioid drugs such as 3'-iodobenzoylnaltrexamide (IBNtxA). Previously, we have shown that IBNtxA is a potent analgesic effective in a spectrum of pain models but lacks many side-effects associated with traditional opiates. In order to investigate the targets labeled by IBNtxA, we synthesized two arylazido analogs of IBNtxA that allow photolabeling of mouse mu opioid receptors (mMOR-1) in transfected cell lines and mMOR-1 protein complexes that may comprise the 6TM sites in mouse brain. We demonstrate that both allyl and alkyne arylazido derivatives of IBNtxA efficiently radio-photolabeled mMOR-1 in cell lines and MOR-1 protein complexes expressed either exogenously or endogenously, as well as found in mouse brain. In future, design and application of such radio-photolabeling ligands with a conjugated handle will provide useful tools for further isolating or purifying MOR-1 to investigate site specific ligand-protein contacts and its signaling complexes.
Collapse
Affiliation(s)
- Steven G Grinnell
- Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center, New York, NY, USA. .,Neuroscience Graduate Program, Weill Cornell Graduate School of Medical Sciences, New York, NY, USA.
| | - Rajendra Uprety
- Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center, New York, NY, USA
| | - Andras Varadi
- Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center, New York, NY, USA.,Neuroscience Graduate Program, Weill Cornell Graduate School of Medical Sciences, New York, NY, USA
| | - Joan Subrath
- Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center, New York, NY, USA
| | - Amanda Hunkele
- Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center, New York, NY, USA
| | - Ying Xian Pan
- Department of Neurology, Memorial Sloan-Kettering Cancer Center, New York, NY, USA.,Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center, New York, NY, USA
| | - Gavril W Pasternak
- Department of Neurology, Memorial Sloan-Kettering Cancer Center, New York, NY, USA.,Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center, New York, NY, USA.,Neuroscience Graduate Program, Weill Cornell Graduate School of Medical Sciences, New York, NY, USA.,Pharmacology Graduate Program, Weill Cornell Graduate School of Medical Sciences, New York, NY, USA
| | - Susruta Majumdar
- Center for Clinical Pharmacology, St Louis College of Pharmacy and Washington University School of Medicine, St Louis, MO, USA.
| |
Collapse
|
4
|
Sun J, Chen SR, Chen H, Pan HL. μ-Opioid receptors in primary sensory neurons are essential for opioid analgesic effect on acute and inflammatory pain and opioid-induced hyperalgesia. J Physiol 2019; 597:1661-1675. [PMID: 30578671 DOI: 10.1113/jp277428] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Accepted: 12/17/2018] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS μ-Opioid receptors (MORs) are expressed peripherally and centrally, but the loci of MORs responsible for clinically relevant opioid analgesia are uncertain. Crossing Oprm1flox/flox and AdvillinCre/+ mice completely ablates MORs in dorsal root ganglion neurons and reduces the MOR expression level in the spinal cord. Presynaptic MORs expressed at primary afferent central terminals are essential for synaptic inhibition and potentiation of sensory input by opioids. MOR ablation in primary sensory neurons diminishes analgesic effects produced by systemic and intrathecal opioid agonists and abolishes chronic opioid treatment-induced hyperalgesia. These findings demonstrate a critical role of MORs expressed in primary sensory neurons in opioid analgesia and suggest new strategies to increase the efficacy and reduce adverse effects of opioids. ABSTRACT The pain and analgesic systems are complex, and the actions of systemically administered opioids may be mediated by simultaneous activation of μ-opioid receptors (MORs, encoded by the Oprm1 gene) at multiple, interacting sites. The loci of MORs and circuits responsible for systemic opioid-induced analgesia and hyperalgesia remain unclear. Previous studies using mice in which MORs are removed from Nav1.8- or TRPV1-expressing neurons provided only an incomplete and erroneous view about the role of peripheral MORs in opioid actions in vivo. In the present study, we determined the specific role of MORs expressed in primary sensory neurons in the analgesic and hyperalgesic effects produced by systemic opioid administration. We generated Oprm1 conditional knockout (Oprm1-cKO) mice in which MOR expression is completely deleted from dorsal root ganglion neurons and substantially reduced in the spinal cord, which was confirmed by immunoblotting and immunocytochemical labelling. Both opioid-induced inhibition and potentiation of primary sensory input were abrogated in Oprm1-cKO mice. Remarkably, systemically administered morphine potently inhibited acute thermal and mechanical nociception and persistent inflammatory pain in control mice but had little effect in Oprm1-cKO mice. The analgesic effect of intrathecally administered morphine was also profoundly reduced in Oprm1-cKO mice. Additionally, chronic morphine treatment-induced hyperalgesia was absent in Oprm1-cKO mice. Our findings directly challenge the notion that clinically relevant opioid analgesia is mediated mostly by centrally expressed MORs. MORs in primary sensory neurons, particularly those expressed presynaptically at the first sensory synapse in the spinal cord, are crucial for both opioid analgesia and opioid-induced hyperalgesia.
Collapse
Affiliation(s)
- Jie Sun
- Center for Neuroscience and Pain Research, Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA.,Department of Anesthesiology, The First Affiliated Hospital/Jiangsu Province Hospital, Nanjing Medical University, Nanjing, Jiangsu, 210029, China
| | - Shao-Rui Chen
- Center for Neuroscience and Pain Research, Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA
| | - Hong Chen
- Center for Neuroscience and Pain Research, Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA
| | - Hui-Lin Pan
- Center for Neuroscience and Pain Research, Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA
| |
Collapse
|
5
|
Abstract
INTRODUCTION Opioids are the oldest and most potent drugs for the treatment of severe pain, but they are burdened by detrimental side effects such as respiratory depression, addiction, sedation, nausea, and constipation. Their clinical application is undisputed in acute (e.g. perioperative) and cancer pain, but their long-term use in chronic pain has met increasing scrutiny and has contributed to the current 'opioid crisis.' AREAS COVERED This article reviews pharmacological principles and research strategies aiming at novel opioids with reduced side effects. Basic mechanisms underlying pain, opioid analgesia, and other opioid actions are outlined. To illustrate the clinical situation and medical needs, plasticity of opioid receptors, intracellular signaling pathways, endogenous and exogenous opioid receptor ligands, central and peripheral sites of analgesic, and side effects are discussed. EXPERT OPINION The epidemic of opioid misuse has taught us that there is a lack of fundamental knowledge about the characteristics and management of chronic pain, that conflicts of interest and validity of models must be considered in the context of drug development, and that novel analgesics with less abuse liability are badly needed. Currently, the most promising perspectives appear to be augmenting endogenous opioid actions and selectively targeting pathological conformations of peripheral opioid receptors.
Collapse
Affiliation(s)
- Christoph Stein
- a Department of Anesthesiology and Intensive Care Medicine Campus Benjamin Franklin , Charité Universitätsmedizin , Berlin , Germany
| |
Collapse
|
6
|
Yan R, Zhang J, Zellmer L, Chen L, Wu D, Liu S, Xu N, Liao JD. Probably less than one-tenth of the genes produce only the wild type protein without at least one additional protein isoform in some human cancer cell lines. Oncotarget 2017; 8:82714-82727. [PMID: 29137297 PMCID: PMC5669923 DOI: 10.18632/oncotarget.20015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Accepted: 06/30/2017] [Indexed: 11/25/2022] Open
Abstract
To estimate how many genes produce multiple protein isoforms, we electrophoresed proteins from MCF7 and MDA-MB231 (MB231) human breast cancer cells in SDS-PAGE and excised narrow stripes of the gel at the 48kD, 55kD and 72kD. Proteins in these stripes were identified using liquid chromatography and tandem mass spectrometry. A total of 765, 750 and 679 proteins from MB231 cells, as well as 470, 390 and 490 proteins from MCF7 cells, were identified from the 48kD, 55kD and 72kD stripes, respectively. We arbitrarily allowed a 10% technical variation from the proteins' theoretical molecular mass (TMM) and considered those proteins with their TMMs within the 43-53 kD, 49-61 kD and 65-79 kD ranges as the wild type (WT) expected from the corresponding stripe, whereas those with a TMM above or below this range as a smaller- or larger-group, respectively. Only 263 (34.4%), 269 (35.9%) and 151 (22.2%) proteins from MB231 cells and 117 (24.9%), 135 (34.6%) and 130 (26.5%) proteins from MCF7 cells from the 48kD, 55kD and 72kD stripes, respectively, belonged to the WT, while the remaining majority belonged to the smaller- or larger-groups. Only about 3-16%, on average about 10% regardless of the stripe and cell line, of the proteins appeared in only one stripe and within the WT range, while the remaining preponderance appeared also in additional stripe(s) or had a larger or smaller TMM. We conclude that few (fewer than 10%) of the human genes produce only the WT protein without additional isoform(s).
Collapse
Affiliation(s)
- Rui Yan
- Nephrology Department, Guizhou Medical University Hospital, Guiyang, P.R. China
| | - Ju Zhang
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, P.R. China
| | - Lucas Zellmer
- Hormel Institute, University of Minnesota, Austin, Minnesota, USA
| | - Lichan Chen
- Hormel Institute, University of Minnesota, Austin, Minnesota, USA
| | - Di Wu
- Beijing Protein Innovation Co., Ltd, Beijing, P.R. China
| | - Siqi Liu
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, P.R. China
| | - Ningzhi Xu
- Laboratory of Cell and Molecular Biology & State Key Laboratory of Molecular Oncology, National Cancer Center/Cancer Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, P.R. China
| | - Joshua D Liao
- Department of Pathology, Guizhou Medical University Hospital, Guiyang, P.R. China
| |
Collapse
|
7
|
Wattiez AS, Walder RY, Sande CM, White SR, Hammond DL. Peripheral inflammatory injury alters the relative abundance of Gα subunits in the dorsal horn of the spinal cord and in the rostral ventromedial medulla of male rats. Mol Pain 2017; 13:1744806917715210. [PMID: 28604220 PMCID: PMC5486491 DOI: 10.1177/1744806917715210] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Abstract A diverse array of G protein-coupled receptors (GPCRs) is implicated in the modulation of nociception. The efficacy and potency of several GPCR agonists change as a consequence of peripheral inflammatory injury. Whether these changes reflect alterations in expression of the G proteins themselves is not known. This study examined the expression of transcripts and proteins for the α subunits of three classes of heteromeric G proteins in the dorsal horn of the spinal cord and the rostral ventromedial medulla (RVM) of male rats four days and two weeks after intraplantar injection of complete Freund’s adjuvant (CFA) or saline. Levels of Gα transcript in the dorsal horn or RVM were unchanged by CFA treatment. However, in the dorsal horn, Gαi protein decreased in cytosolic and membrane fractions four days after CFA treatment. Levels of Gαz protein decreased in the membrane fraction. Levels of the other Gα subunits did not differ. Levels of the Gα subunits were unchanged two weeks after CFA treatment. In the RVM, Gαz protein levels decreased in the cytosolic fraction four days after CFA treatment. No other differences were observed. Two weeks after CFA, the levels for all Gα subunits trended higher in the RVM. These data indicate that peripheral inflammatory injury induces subtle changes in the abundance of Gα subunits that is specific with respect to class, subcellular compartment, tissue, and time after injury. These changes have the potential to alter the balance of the different subcellular signaling pathways through which GPCR agonists act to modulate nociception.
Collapse
|
8
|
Mambretti EM, Kistner K, Mayer S, Massotte D, Kieffer BL, Hoffmann C, Reeh PW, Brack A, Asan E, Rittner HL. Functional and structural characterization of axonal opioid receptors as targets for analgesia. Mol Pain 2016; 12:12/0/1744806916628734. [PMID: 27030709 PMCID: PMC4994859 DOI: 10.1177/1744806916628734] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Accepted: 10/10/2015] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Opioids are the gold standard for the treatment of acute pain despite serious side effects in the central and enteric nervous system. µ-opioid receptors (MOPs) are expressed and functional at the terminals of sensory axons, when activated by exogenous or endogenous ligands. However, the presence and function of MOP along nociceptive axons remains controversial particularly in naïve animals. Here, we characterized axonal MOPs by immunofluorescence, ultrastructural, and functional analyses. Furthermore, we evaluated hypertonic saline as a possible enhancer of opioid receptor function. RESULTS Comparative immunolabeling showed that, among several tested antibodies, which all provided specific MOP detection in the rat central nervous system (CNS), only one monoclonal MOP-antibody yielded specificity and reproducibility for MOP detection in the rat peripheral nervous system including the sciatic nerve. Double immunolabeling documented that MOP immunoreactivity was confined to calcitonin gene-related peptide (CGRP) positive fibers and fiber bundles. Almost identical labeling and double labeling patterns were found using mcherry-immunolabeling on sciatic nerves of mice producing a MOP-mcherry fusion protein (MOP-mcherry knock-in mice). Preembedding immunogold electron microscopy on MOP-mcherry knock-in sciatic nerves indicated presence of MOP in cytoplasm and at membranes of unmyelinated axons. Application of [D-Ala(2), N-MePhe(4), Gly-ol]-enkephalin (DAMGO) or fentanyl dose-dependently inhibited depolarization-induced CGRP release from rat sciatic nerve axons ex vivo, which was blocked by naloxone. When the lipophilic opioid fentanyl was applied perisciatically in naïve Wistar rats, mechanical nociceptive thresholds increased. Subthreshold doses of fentanyl or the hydrophilic opioid DAMGO were only effective if injected together with hypertonic saline. In vitro, using β-arrestin-2/MOP double-transfected human embryonic kidney cells, DAMGO as well as fentanyl lead to a recruitment of β-arrestin-2 to the membrane followed by a β-arrestin-2 reappearance in the cytosol and MOP internalization. Pretreatment with hypertonic saline prevented MOP internalization. CONCLUSION MOPs are present and functional in the axonal membrane from naïve animals. Hypertonic saline acutely decreases ligand-induced internalization of MOP and thereby might improve MOP function. Further studies should explore potential clinical applications of opioids together with enhancers for regional analgesia.
Collapse
Affiliation(s)
- Egle M Mambretti
- Department of Anesthesiology, University Hospital of Wuerzburg, Germany Institute of Anatomy and Cell Biology, University of Wuerzburg, Germany
| | - Katrin Kistner
- Institute of Physiology and Pathophysiology, University of Erlangen-Nuremberg, Germany
| | - Stefanie Mayer
- Institute for Pharmacology and Toxicology & Bio-Imaging Center/Rudolf-Virchow Center, University of Wuerzburg, Germany
| | - Dominique Massotte
- Institut des Neurosciences Cellulaires et Intégratives, CNRS UPR, Strasbourg Cedex, France
| | - Brigitte L Kieffer
- Douglas Research Center, Department of Psychiatry, Faculty of Medicine, McGill University, Montreal, Quebec, Canada Institut de Génétique et de Biologie Moléculaire et Cellulaire, Université de Strasbourg, Illkirch, France
| | - Carsten Hoffmann
- Institute for Pharmacology and Toxicology & Bio-Imaging Center/Rudolf-Virchow Center, University of Wuerzburg, Germany
| | - Peter W Reeh
- Institute of Physiology and Pathophysiology, University of Erlangen-Nuremberg, Germany
| | - Alexander Brack
- Department of Anesthesiology, University Hospital of Wuerzburg, Germany
| | - Esther Asan
- Institute of Anatomy and Cell Biology, University of Wuerzburg, Germany
| | - Heike L Rittner
- Department of Anesthesiology, University Hospital of Wuerzburg, Germany
| |
Collapse
|