1
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Konofal E. From past to future: 50 years of pharmacological interventions to treat narcolepsy. Pharmacol Biochem Behav 2024; 241:173804. [PMID: 38852786 DOI: 10.1016/j.pbb.2024.173804] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2024] [Revised: 05/29/2024] [Accepted: 06/01/2024] [Indexed: 06/11/2024]
Abstract
The history of narcolepsy research began with the pioneering work of Jean-Baptiste-Édouard Gélineau in the late 19th century. In the 1880s, Gélineau introduced the term "narcolepsy" to describe a condition characterized by sudden and uncontrollable episodes of sleep. His clinical descriptions laid the foundation for our understanding of this complex disorder. Over the last half-century, the pharmacological landscape for narcolepsy treatment has evolved remarkably, shifting from merely managing symptoms to increasingly targeting its underlying pathophysiology. By the 1930s, treatments such as ephedrine and amphetamine were introduced to alleviate excessive daytime sleepiness, marking significant advancements in narcolepsy management. These stimulants provided temporary relief, helping patients maintain wakefulness during the day. As research progressed, the focus shifted towards understanding the disorder's underlying mechanisms. The discovery of orexin (also known as hypocretin) in the late 1990s revolutionized the field. This breakthrough underscored the importance of orexin in regulating sleep-wake cycles and provided new targets for pharmacological intervention. Looking ahead, the future of narcolepsy pharmacotherapy is poised for further innovation. The ongoing exploration of orexin receptor agonists and the potential development of neuroprotective therapeutic targets underscore a promising horizon. Emerging research into the genetic and immunological underpinnings of narcolepsy opens new avenues for personalized medicine approaches and the identification of biomarkers for more precise treatment strategies. Additionally, the refinement of existing treatments through improved delivery systems and the investigation of combination therapies offer opportunities for enhanced efficacy and improved quality of life for patients with narcolepsy.
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Affiliation(s)
- Eric Konofal
- Centre Pédiatrique des Pathologies du Sommeil, APHP Hôpital Robert Debré, 48 Boulevard Sérurier, Paris 75019, France.
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2
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Servant G, Kenakin T. A Pharmacological perspective on the temporal properties of sweeteners. Pharmacol Res 2024; 204:107211. [PMID: 38744400 DOI: 10.1016/j.phrs.2024.107211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2024] [Revised: 05/06/2024] [Accepted: 05/09/2024] [Indexed: 05/16/2024]
Abstract
Several non-caloric sweeteners exhibit a delay in sweetness onset and a sweetness linger after sampling. These temporal properties are thought to be the result of non-specific interactions with cell membranes and proteins in the oral cavity. Data and analysis presented in this report also support the potential involvement of receptor affinity and binding kinetics to this phenomenon. In general, affected sweeteners exhibit distinctly higher binding affinity compared to carbohydrate sweeteners, which do not have temporal issues. In addition, binding kinetic simulations illustrate much slower receptor binding association and dissociation kinetics for a set of non-caloric sweeteners presenting temporal issues, in comparison to carbohydrate sweeteners. So, the higher affinity of some non-caloric sweeteners, dictating lower use levels, and affecting binding kinetics, could contribute to their delay and linger in sweetness perception. Simple pharmacology principles could explain, at least in part, some of the temporal issues of sweeteners.
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Affiliation(s)
- Guy Servant
- dsm-firmenich, 10636 Scripps Summit Court #201, San Diego, CA 92131, USA.
| | - Terry Kenakin
- Department of Pharmacology, University of North Carolina School of Medicine, 120 Mason Farm Rd., 4042 Genetic Medicine CB #7365, Chapel Hill, NC 27599, USA
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3
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Hicks C, Gardner J, Eiger DS, Camarda ND, Pham U, Dhar S, Rodriguez H, Chundi A, Rajagopal S. ACKR3 Proximity Labeling Identifies Novel G protein- and β-arrestin-independent GPCR Interacting Proteins. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.27.577545. [PMID: 38410489 PMCID: PMC10896341 DOI: 10.1101/2024.01.27.577545] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/28/2024]
Abstract
The canonical paradigm of GPCR signaling recognizes G proteins and β-arrestins as the two primary transducers that promote GPCR signaling. Recent evidence suggests the atypical chemokine receptor 3 (ACKR3) does not couple to G proteins, and β-arrestins are dispensable for some of its functions. Here, we employed proximity labeling to identify proteins that interact with ACKR3 in cells devoid of β-arrestin. We identified proteins involved in the endocytic machinery and evaluated a subset of proteins conserved across several GPCR-based proximity labeling experiments. We discovered that the bone morphogenic protein 2-inducible kinase (BMP2K) interacts with many different GPCRs with varying dependency on β-arrestin. Together, our work highlights the existence of modulators that can act independently of G proteins and β-arrestins to regulate GPCR signaling and provides important evidence for other targets that may regulate GPCR signaling.
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Affiliation(s)
- Chloe Hicks
- National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Julia Gardner
- Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Dylan Scott Eiger
- Department of Medicine, Brigham and Women’s Hospital, Boston, MA, 02215, USA
- Harvard Medical School, Boston, MA, 02215, USA
| | - Nicholas D. Camarda
- Genetics, Molecular, and Cellular Biology Program, Tufts Graduate School of Biomedical Sciences, Boston, MA, 02111, USA
| | - Uyen Pham
- Department of Biochemistry, Duke University, Durham, NC, 27710, USA
| | - Saisha Dhar
- Trinity College, Duke University, Durham, NC, 27710, USA
| | | | - Anand Chundi
- Pratt School of Engineering, Duke University, Durham, NC, 27710, USA
| | - Sudarshan Rajagopal
- Department of Biochemistry, Duke University, Durham, NC, 27710, USA
- Department of Medicine, Duke University, Durham, NC, 27710, USA
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4
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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: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [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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5
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GRKs as Key Modulators of Opioid Receptor Function. Cells 2020; 9:cells9112400. [PMID: 33147802 PMCID: PMC7692057 DOI: 10.3390/cells9112400] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 10/21/2020] [Accepted: 10/28/2020] [Indexed: 12/21/2022] Open
Abstract
Understanding the link between agonist-induced phosphorylation of the mu-opioid receptor (MOR) and the associated physiological effects is critical for the development of novel analgesic drugs and is particularly important for understanding the mechanisms responsible for opioid-induced tolerance and addiction. The family of G protein receptor kinases (GRKs) play a pivotal role in such processes, mediating phosphorylation of residues at the C-tail of opioid receptors. Numerous strategies, such as phosphosite specific antibodies and mass spectrometry have allowed the detection of phosphorylated residues and the use of mutant knock-in mice have shed light on the role of GRK regulation in opioid receptor physiology. Here we review our current understanding on the role of GRKs in the actions of opioid receptors, with a particular focus on the MOR, the target of most commonly used opioid analgesics such as morphine or fentanyl.
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6
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Brimson JM, Akula KK, Abbas H, Ferry DR, Kulkarni SK, Russell ST, Tisdale MJ, Tencomnao T, Safrany ST. Simple ammonium salts acting on sigma-1 receptors yield potential treatments for cancer and depression. Sci Rep 2020; 10:9251. [PMID: 32514120 PMCID: PMC7280195 DOI: 10.1038/s41598-020-65849-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Accepted: 05/06/2020] [Indexed: 01/11/2023] Open
Abstract
Sigma-1 and sigma-2 receptors are emerging therapeutic targets. We have identified that simple ammonium salts bind to these receptors and are effective in vivo. Radioligand binding assays were used to obtain structure-activity relationships of these salts. MTS assays were performed to determine their effect on growth in MCF7 and MDA-MB-486 cells. Anticancer properties were tested in NMRI mice transplanted with a fragment of mouse adenocarcinoma (MAC13). Antidepressant activity was tested using the forced-swim test and tail suspension tests. Dipentylammonium (Ki 43 nM), tripentylammonium (Ki 15 nM) and trihexylammonium (Ki 9 nM) showed high affinity for the sigma-1 receptor. Dioctanoylammonium had the highest affinity (K50 0.05 nM); this also showed the highest affinity for sigma-2 receptors (Ki 13 nM). Dipentylammonium was found to have antidepressant activity in vivo. Branched-chain ammonium salts showed lower affinity. Bis(2-ethylhexyl)ammonium (K50 29 µM), triisopentylammonium (K50 196 µM) and dioctanoylammonium showed a low Hill slope, and fitted a 2-site binding model for the sigma-1 receptor. We propose this two-site binding can be used to biochemically define a sigma-1 receptor antagonist. Bis(2-ethylhexyl)ammonium and triisopentylammonium were able to inhibit the growth of tumours in vivo. Cheap, simple ammonium salts act as sigma-1 receptor agonists and antagonists in vivo and require further investigation.
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Affiliation(s)
- James M Brimson
- Age-Related Inflammation and Degeneration Research Unit, Department of Clinical Chemistry, Faculty of Allied Health Sciences, Chulalongkorn University, Bangkok, 10330, Thailand
- Department of Pharmacy and Pharmacology, University of Bath, Claverton Down, Bath, BA2 7AY, UK
| | - Kiran K Akula
- University Institute of Pharmaceutical Sciences, Panjab University, Chandigarh, 160014, India
- Ultragenyx Pharmaceuticals Inc, Novato, California, CA94949, USA
| | - Haider Abbas
- Department of Pharmacy, University of Wolverhampton, Wulfruna Street, Wolverhampton, WV1 1LY, UK
- New Cross Hospital, Wolverhampton, WV10 0QP, UK
- University Hospital Birmingham NHS Foundation Trust, Mindelsohn Way, Birmingham, B15 2TH, UK
| | - David R Ferry
- Eli Lilly, 893 S Delaware Street, Indianapolis, IN, 46225, USA
| | - Shrinivas K Kulkarni
- University Institute of Pharmaceutical Sciences, Panjab University, Chandigarh, 160014, India
| | - Steven T Russell
- School of Health and Life Sciences, Aston University, Birmingham, B4 7ET, UK
| | - Michael J Tisdale
- School of Health and Life Sciences, Aston University, Birmingham, B4 7ET, UK
| | - Tewin Tencomnao
- Age-Related Inflammation and Degeneration Research Unit, Department of Clinical Chemistry, Faculty of Allied Health Sciences, Chulalongkorn University, Bangkok, 10330, Thailand
| | - Stephen T Safrany
- Department of Pharmacy and Pharmacology, University of Bath, Claverton Down, Bath, BA2 7AY, UK.
- Department of Pharmacy, University of Wolverhampton, Wulfruna Street, Wolverhampton, WV1 1LY, UK.
- RCSI-Bahrain, PO Box 15503, Adliya, Kingdom of Bahrain.
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7
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Ziffert I, Kaiser A, Babilon S, Mörl K, Beck-Sickinger AG. Unusually persistent Gα i-signaling of the neuropeptide Y 2 receptor depletes cellular G i/o pools and leads to a G i-refractory state. Cell Commun Signal 2020; 18:49. [PMID: 32223755 PMCID: PMC7104545 DOI: 10.1186/s12964-020-00537-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2019] [Accepted: 02/19/2020] [Indexed: 01/14/2023] Open
Abstract
BACKGROUND A sensitive balance between receptor activation and desensitization is crucial for cellular homeostasis. Like many other GPCR, the human neuropeptide Y2 receptor (hY2R) undergoes ligand dependent activation and internalization into intracellular compartments, followed by recycling to the plasma membrane. This receptor is involved in the pathophysiology of distinct diseases e.g. epilepsy and cancer progression and conveys anorexigenic signals which makes it an interesting and promising anti-obesity target. However, Y2R desensitization was observed after daily treatment with a selective PYY13-36 analog in vivo by a yet unknown mechanism. MATERIALS We studied the desensitization and activatability of recycled Y2R in transiently transfected HEK293 cells as well as in endogenously Y2R expressing SH-SY5Y and SMS-KAN cells. Results were evaluated by one-way ANOVA and Tukey post test. RESULTS We observed strong desensitization of the Y2R in a second round of stimulation despite its reappearance at the membrane. Already the first activation of the Y2R leads to depletion of the functional cellular Gαi/o protein pool and consequently desensitizes the linked signal transduction pathways, independent of receptor internalization. This desensitization also extends to other Gαi/o-coupled GPCR and can be detected in transfected HEK293 as well as in SH-SY5Y and SMS-KAN cell lines, both expressing the Y2R endogenously. By overexpression of chimeric Gαqi proteins in a model system, activation has been rescued, which identifies a critical role of the G protein status for cellular signaling. Furthermore, Y2R displays strong allosteric coupling to inhibitory G proteins in radioligand binding assays, and loses 10-fold affinity in the G protein-depleted state observed after activation, which can be largely abrogated by overexpression of the Gαi-subunit. CONCLUSION The unusually persistent Gαi-signaling of the Y2R leads to a state of cellular desensitization of the inhibitory Gαi-pathway. The strong allosteric effects of the Y2R-Gαi-interaction might be a mechanism that contributes to the burst of Gαi-signaling, but also serves as a mechanism to limit the Y2-mediated signaling after recycling. Thus, the cell is left in a refractory state, preventing further Gαi-signaling of the Y2R itself but also other Gαi/o-coupled receptors by simply controlling the repertoire of downstream effectors. Video abstract.
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Affiliation(s)
- Isabelle Ziffert
- Institute of Biochemistry, Faculty of Life Sciences, Leipzig University, Brüderstr. 34, D-04103, Leipzig, Germany
| | - Anette Kaiser
- Institute of Biochemistry, Faculty of Life Sciences, Leipzig University, Brüderstr. 34, D-04103, Leipzig, Germany
| | - Stefanie Babilon
- Institute of Biochemistry, Faculty of Life Sciences, Leipzig University, Brüderstr. 34, D-04103, Leipzig, Germany
| | - Karin Mörl
- Institute of Biochemistry, Faculty of Life Sciences, Leipzig University, Brüderstr. 34, D-04103, Leipzig, Germany
| | - Annette G Beck-Sickinger
- Institute of Biochemistry, Faculty of Life Sciences, Leipzig University, Brüderstr. 34, D-04103, Leipzig, Germany.
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8
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Birdsong WT, Williams JT. Recent Progress in Opioid Research from an Electrophysiological Perspective. Mol Pharmacol 2020; 98:401-409. [PMID: 32198208 PMCID: PMC7562972 DOI: 10.1124/mol.119.119040] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2019] [Accepted: 03/12/2020] [Indexed: 02/06/2023] Open
Abstract
Electrophysiological approaches provide powerful tools to further our understanding of how different opioids affect signaling through opioid receptors; how opioid receptors modulate circuitry involved in processes such as pain, respiration, addiction, and feeding; and how receptor signaling and circuits are altered by physiologic challenges, such as injury, stress, and chronic opioid treatment. The use of genetic manipulations to alter or remove μ-opioid receptors (MORs) with anatomic and cell type specificity and the ability to activate or inhibit specific circuits through opto- or chemogenetic approaches are being used in combination with electrophysiological, pharmacological, and systems-level physiology experiments to expand our understanding of the beneficial and maladaptive roles of opioids and opioid receptor signaling. New approaches for studying endogenous opioid peptide signaling and release and the dynamics of these systems in response to chronic opioid use, pain, and stress will add another layer to our understanding of the intricacies of opioid modulation of brain circuits. This understanding may lead to new targets or approaches for drug development or treatment regimens that may affect both acute and long-term effects of manipulating the activity of circuits involved in opioid-mediated physiology and behaviors. This review will discuss recent advancements in our understanding of the role of phosphorylation in regulating MOR signaling, as well as our understanding of circuits and signaling pathways mediating physiologic behaviors such as respiratory control, and discuss how electrophysiological tools combined with new technologies have and will continue to advance the field of opioid research.
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Affiliation(s)
- William T Birdsong
- Department of Pharmacology, University of Michigan, Ann Arbor, Michigan (W.T.B.) and Vollum Institute, Oregon Health & Science University, Portland, Oregon (J.T.W.)
| | - John T Williams
- Department of Pharmacology, University of Michigan, Ann Arbor, Michigan (W.T.B.) and Vollum Institute, Oregon Health & Science University, Portland, Oregon (J.T.W.)
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9
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Jullié D, Stoeber M, Sibarita JB, Zieger HL, Bartol TM, Arttamangkul S, Sejnowski TJ, Hosy E, von Zastrow M. A Discrete Presynaptic Vesicle Cycle for Neuromodulator Receptors. Neuron 2020; 105:663-677.e8. [PMID: 31837915 PMCID: PMC7035187 DOI: 10.1016/j.neuron.2019.11.016] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Revised: 08/02/2019] [Accepted: 11/11/2019] [Indexed: 01/27/2023]
Abstract
A major function of GPCRs is to inhibit presynaptic neurotransmitter release, requiring ligand-activated receptors to couple locally to effectors at terminals. The current understanding of how this is achieved is through receptor immobilization on the terminal surface. Here, we show that opioid peptide receptors, GPCRs that mediate highly sensitive presynaptic inhibition, are instead dynamic in axons. Opioid receptors diffuse rapidly throughout the axon surface and internalize after ligand-induced activation specifically at presynaptic terminals. We delineate a parallel regulated endocytic cycle for GPCRs operating at the presynapse, separately from the synaptic vesicle cycle, which clears activated receptors from the surface of terminals and locally reinserts them to maintain the diffusible surface pool. We propose an alternate strategy for achieving local control of presynaptic effectors that, opposite to using receptor immobilization and enforced proximity, is based on lateral mobility of receptors and leverages the inherent allostery of GPCR-effector coupling.
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Affiliation(s)
- Damien Jullié
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco School of Medicine, San Francisco, California 94158, USA,Department of Psychiatry, University of California, San Francisco School of Medicine, San Francisco, California 94158, USA
| | - Miriam Stoeber
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco School of Medicine, San Francisco, California 94158, USA,Department of Psychiatry, University of California, San Francisco School of Medicine, San Francisco, California 94158, USA,Department of Cell Physiology and Metabolism, University of Geneva, 1211 Geneva, Switzerland
| | - Jean-Baptiste Sibarita
- Interdisciplinary Institute for Neuroscience, UMR 5297, Centre National de la Recherche Scientifique, 33077 Bordeaux, France,Interdisciplinary Institute for Neuroscience, University of Bordeaux, 33077 Bordeaux, France
| | - Hanna L. Zieger
- Interdisciplinary Institute for Neuroscience, UMR 5297, Centre National de la Recherche Scientifique, 33077 Bordeaux, France,Interdisciplinary Institute for Neuroscience, University of Bordeaux, 33077 Bordeaux, France
| | - Thomas M. Bartol
- Howard Hughes Medical Institute, Salk Institute for Biological Studies, La Jolla, California 92037, USA
| | - Seksiri Arttamangkul
- The Vollum Institute, Oregon Health and Science University, Portland, Oregon 97239, USA
| | - Terrence J. Sejnowski
- Howard Hughes Medical Institute, Salk Institute for Biological Studies, La Jolla, California 92037, USA
| | - Eric Hosy
- Interdisciplinary Institute for Neuroscience, UMR 5297, Centre National de la Recherche Scientifique, 33077 Bordeaux, France,Interdisciplinary Institute for Neuroscience, University of Bordeaux, 33077 Bordeaux, France
| | - Mark von Zastrow
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco School of Medicine, San Francisco, California 94158, USA,Department of Psychiatry, University of California, San Francisco School of Medicine, San Francisco, California 94158, USA,Lead contact,Correspondence:
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10
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Arttamangkul S, Plazek A, Platt EJ, Jin H, Murray TF, Birdsong WT, Rice KC, Farrens DL, Williams JT. Visualizing endogenous opioid receptors in living neurons using ligand-directed chemistry. eLife 2019; 8:49319. [PMID: 31589142 PMCID: PMC6809603 DOI: 10.7554/elife.49319] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Accepted: 10/06/2019] [Indexed: 12/11/2022] Open
Abstract
Identifying neurons that have functional opioid receptors is fundamental for the understanding of the cellular, synaptic and systems actions of opioids. Current techniques are limited to post hoc analyses of fixed tissues. Here we developed a fluorescent probe, naltrexamine-acylimidazole (NAI), to label opioid receptors based on a chemical approach termed ‘traceless affinity labeling’. In this approach, a high affinity antagonist naltrexamine is used as the guide molecule for a transferring reaction of acylimidazole at the receptor. This reaction generates a fluorescent dye covalently linked to the receptor while naltrexamine is liberated and leaves the binding site. The labeling induced by this reagent allowed visualization of opioid-sensitive neurons in rat and mouse brains without loss of function of the fluorescently labeled receptors. The ability to locate endogenous receptors in living tissues will aid considerably in establishing the distribution and physiological role of opioid receptors in the CNS of wild type animals.
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Affiliation(s)
- Seksiri Arttamangkul
- The Vollum Institute, Oregon Health & Science University, Portland, United States
| | - Andrew Plazek
- Medicinal Chemistry Core, Oregon Health & Science University, Portland, United States
| | - Emily J Platt
- Department of Biochemistry and Molecular Biology, School of Medicine, Oregon Health & Science University, Portland, United States
| | - Haihong Jin
- Medicinal Chemistry Core, Oregon Health & Science University, Portland, United States
| | - Thomas F Murray
- Department of Pharmacology, School of Medicine, Creighton University, Omaha, United States
| | - William T Birdsong
- The Vollum Institute, Oregon Health & Science University, Portland, United States
| | - Kenner C Rice
- Drug Design and Synthesis Section, Intramural Research Program, NIDA and NIAAA, Bethesda, United States
| | - David L Farrens
- Department of Biochemistry and Molecular Biology, School of Medicine, Oregon Health & Science University, Portland, United States
| | - John T Williams
- The Vollum Institute, Oregon Health & Science University, Portland, United States
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11
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Ciotu CI, Tsantoulas C, Meents J, Lampert A, McMahon SB, Ludwig A, Fischer MJM. Noncanonical Ion Channel Behaviour in Pain. Int J Mol Sci 2019; 20:E4572. [PMID: 31540178 PMCID: PMC6770626 DOI: 10.3390/ijms20184572] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Revised: 09/09/2019] [Accepted: 09/12/2019] [Indexed: 12/19/2022] Open
Abstract
Ion channels contribute fundamental properties to cell membranes. Although highly diverse in conductivity, structure, location, and function, many of them can be regulated by common mechanisms, such as voltage or (de-)phosphorylation. Primarily considering ion channels involved in the nociceptive system, this review covers more novel and less known features. Accordingly, we outline noncanonical operation of voltage-gated sodium, potassium, transient receptor potential (TRP), and hyperpolarization-activated cyclic nucleotide (HCN)-gated channels. Noncanonical features discussed include properties as a memory for prior voltage and chemical exposure, alternative ion conduction pathways, cluster formation, and silent subunits. Complementary to this main focus, the intention is also to transfer knowledge between fields, which become inevitably more separate due to their size.
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Affiliation(s)
- Cosmin I Ciotu
- Center for Physiology and Pharmacology, Medical University of Vienna, 1090 Vienna, Austria
| | | | - Jannis Meents
- Institute of Physiology, University Hospital RWTH Aachen, 52074 Aachen, Germany
| | - Angelika Lampert
- Institute of Physiology, University Hospital RWTH Aachen, 52074 Aachen, Germany
| | - Stephen B McMahon
- Wolfson Centre for Age-Related Diseases, King's College London, London SE1 1UR, UK
| | - Andreas Ludwig
- Institute of Experimental and Clinical Pharmacology and Toxicology, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany
| | - Michael J M Fischer
- Center for Physiology and Pharmacology, Medical University of Vienna, 1090 Vienna, Austria.
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12
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Arttamangkul S, Leff ER, Koita O, Birdsong WT, Williams JT. Separation of Acute Desensitization and Long-Term Tolerance of µ-Opioid Receptors Is Determined by the Degree of C-Terminal Phosphorylation. Mol Pharmacol 2019; 96:505-514. [PMID: 31383769 DOI: 10.1124/mol.119.117358] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Accepted: 08/02/2019] [Indexed: 01/22/2023] Open
Abstract
Phosphorylation of sites on the C terminus of the μ-opioid receptor (MOR) results in the induction of acute desensitization that is thought to be a precursor for the development of long-term tolerance. Alanine mutations of all 11 phosphorylation sites on the C terminus of MORs almost completely abolished desensitization and one measure of tolerance in locus coeruleus neurons when these phosphorylation-deficient MORs were virally expressed in MOR knockout rats. In the present work, we identified specific residues that underlie acute desensitization, receptor internalization, and tolerance and examined four MOR variants with different alanine or glutamate mutations in the C terminus. Alanine mutations in the sequence between amino acids 375 and 379 (STANT-3A) and the sequence between amino acids 363 and 394 having four additional alanine substitutions (STANT + 7A) reduced desensitization and two measures of long-term tolerance. After chronic morphine treatment, alanine mutations in the sequence between 354 and 357 (TSST-4A) blocked one measure of long-term tolerance (increased acute desensitization and slowed recovery from desensitization) but did not change a second (decreased sensitivity to morphine). With the expression of receptors having glutamate substitutions in the TSST sequence (TSST-4E), an increase in acute desensitization was present after chronic morphine treatment, but the sensitivity to morphine was not changed. The results show that all 11 phosphorylation sites contribute, in varying degrees, to acute desensitization and long-term tolerance. That acute desensitization and tolerance are not necessarily linked illustrates the complexity of events that are triggered by chronic treatment with morphine. SIGNIFICANCE STATEMENT: In this work, we showed that the degree of phosphorylation on the C terminus of the μ-opioid receptor alters acute desensitization and internalization, and in measures of long-term tolerance to morphine. The primary conclusion is that the degree of phosphorylation on the 11 possible sites of the C terminus has different roles for expression of the multiple adaptive mechanisms that follow acute and long-term agonist activation. Although the idea that acute desensitization and tolerance are intimately linked is generally supported, these results indicate that disruption of one phosphorylation cassette of the C terminus TSST (354-357) distinguishes the two processes.
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Affiliation(s)
| | - Emily R Leff
- Vollum Institute, Oregon Health & Science University, Portland, Oregon
| | - Omar Koita
- Vollum Institute, Oregon Health & Science University, Portland, Oregon
| | | | - John T Williams
- Vollum Institute, Oregon Health & Science University, Portland, Oregon
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13
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Ganzer PD, Beringer CR, Shumsky JS, Nwaobasi C, Moxon KA. Serotonin receptor and dendritic plasticity in the spinal cord mediated by chronic serotonergic pharmacotherapy combined with exercise following complete SCI in the adult rat. Exp Neurol 2018. [PMID: 29526741 DOI: 10.1016/j.expneurol.2018.03.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Severe spinal cord injury (SCI) damages descending motor and serotonin (5-HT) fiber projections leading to paralysis and serotonin depletion. 5-HT receptors (5-HTRs) subsequently upregulate following 5-HT fiber degeneration, and dendritic density decreases indicative of atrophy. 5-HT pharmacotherapy or exercise can improve locomotor behavior after SCI. One might expect that 5-HT pharmacotherapy acts on upregulated spinal 5-HTRs to enhance function, and that exercise alone can influence dendritic atrophy. In the current study, we assessed locomotor recovery and spinal proteins influenced by SCI and therapy. 5-HT, 5-HT2AR, 5-HT1AR, and dendritic densities were quantified both early (1 week) and late (9 weeks) after SCI, and also following therapeutic interventions (5-HT pharmacotherapy, bike therapy, or a combination). Interestingly, chronic 5-HT pharmacotherapy largely normalized spinal 5-HTR upregulation following injury. Improvement in locomotor behavior was not correlated to 5-HTR density. These results support the hypothesis that chronic 5-HT pharmacotherapy can mediate recovery following SCI, despite acting on largely normal spinal 5-HTR levels. We next assessed spinal dendritic plasticity and its potential role in locomotor recovery. Single therapies did not normalize the loss of dendritic density after SCI. Groups displaying significantly atrophied dendritic processes were rarely able to achieve weight supported open-field locomotion. Only a combination of 5-HT pharmacotherapy and bike therapy enabled significant open-field weigh-supported stepping, mediated in part by restoring spinal dendritic density. These results support the use of combined therapies to synergistically impact multiple markers of spinal plasticity and improve motor recovery.
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Affiliation(s)
- Patrick D Ganzer
- School of Biomedical Engineering, Science and Health Systems, Drexel University, 3141 Chestnut St., Philadelphia, PA 19104, United States.
| | - Carl R Beringer
- School of Biomedical Engineering, Science and Health Systems, Drexel University, 3141 Chestnut St., Philadelphia, PA 19104, United States
| | - Jed S Shumsky
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, 2900 Queen Lane, Philadelphia, PA 19129, United States
| | - Chiemela Nwaobasi
- School of Biomedical Engineering, Science and Health Systems, Drexel University, 3141 Chestnut St., Philadelphia, PA 19104, United States
| | - Karen A Moxon
- School of Biomedical Engineering, Science and Health Systems, Drexel University, 3141 Chestnut St., Philadelphia, PA 19104, United States; Department of Neurobiology and Anatomy, Drexel University College of Medicine, 2900 Queen Lane, Philadelphia, PA 19129, United States
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14
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Montpas N, St-Onge G, Nama N, Rhainds D, Benredjem B, Girard M, Hickson G, Pons V, Heveker N. Ligand-specific conformational transitions and intracellular transport are required for atypical chemokine receptor 3-mediated chemokine scavenging. J Biol Chem 2017; 293:893-905. [PMID: 29180449 PMCID: PMC5777261 DOI: 10.1074/jbc.m117.814947] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Revised: 11/20/2017] [Indexed: 11/06/2022] Open
Abstract
The atypical chemokine receptor ACKR3 contributes to chemotaxis by binding, internalizing, and degrading the chemokines CXCL11 and CXCL12 to shape and terminate chemotactic gradients during development and immune responses. Although unable to trigger G protein activation, both ligands activate G protein-independent ACKR3 responses and prompt arrestin recruitment. This offers a model to specifically study ligand-specific receptor conformations leading to G protein-independent signaling and to functional parameters such as receptor transport and chemokine degradation. We here show chemokine specificity in arrestin recruitment, by different effects of single amino acid substitutions in ACKR3 on arrestin in response to CXCL12 or CXCL11. Chemokine specificity in receptor transport was also observed, as CXCL11 induced faster receptor internalization, slower recycling, and longer intracellular sojourn of ACKR3 than CXCL12. Internalization and recycling rates of the ACKR3 R1423.50A substitution in response to each chemokine were similar; however, ACKR3 R1423.50A degraded only CXCL12 and not CXCL11. This suggests that ligand-specific intracellular receptor transport is required for chemokine degradation. Remarkably, the failure of ACKR3 R1423.50A to degrade CXCL11 was not caused by the lack of arrestin recruitment; rather, arrestin was entirely dispensable for scavenging of either chemokine. This suggests the involvement of another, yet unidentified, ACKR3 effector in scavenging. In summary, our study correlates ACKR3 ligand-specific conformational transitions with chemokine-dependent receptor transport dynamics and points toward unexpected ligand specificity in the mechanisms of chemokine degradation.
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Affiliation(s)
- Nicolas Montpas
- From the Department of Biochemistry and Molecular Medicine, University of Montréal, Montréal, Quebec H3T 1J4, Canada.,the Research Centre, Saint-Justine Hospital, University of Montréal, Montréal, Quebec H3T 1C5, Canada
| | - Geneviève St-Onge
- the Research Centre, Saint-Justine Hospital, University of Montréal, Montréal, Quebec H3T 1C5, Canada
| | - Nassr Nama
- From the Department of Biochemistry and Molecular Medicine, University of Montréal, Montréal, Quebec H3T 1J4, Canada.,the Research Centre, Saint-Justine Hospital, University of Montréal, Montréal, Quebec H3T 1C5, Canada
| | - David Rhainds
- From the Department of Biochemistry and Molecular Medicine, University of Montréal, Montréal, Quebec H3T 1J4, Canada.,the Research Centre, Saint-Justine Hospital, University of Montréal, Montréal, Quebec H3T 1C5, Canada
| | - Besma Benredjem
- From the Department of Biochemistry and Molecular Medicine, University of Montréal, Montréal, Quebec H3T 1J4, Canada.,the Research Centre, Saint-Justine Hospital, University of Montréal, Montréal, Quebec H3T 1C5, Canada
| | - Mélanie Girard
- From the Department of Biochemistry and Molecular Medicine, University of Montréal, Montréal, Quebec H3T 1J4, Canada.,the Research Centre, Saint-Justine Hospital, University of Montréal, Montréal, Quebec H3T 1C5, Canada
| | - Gilles Hickson
- the Research Centre, Saint-Justine Hospital, University of Montréal, Montréal, Quebec H3T 1C5, Canada.,the Department of Pathology and Cell Biology, University of Montréal, Montréal, Quebec H3T 1J4, Canada, and
| | - Véronique Pons
- INSERM, UMR 1048, Institut des Maladies Métaboliques et Cardiovasculaires, Université de Toulouse, F-31432 Toulouse, France
| | - Nikolaus Heveker
- From the Department of Biochemistry and Molecular Medicine, University of Montréal, Montréal, Quebec H3T 1J4, Canada, .,the Research Centre, Saint-Justine Hospital, University of Montréal, Montréal, Quebec H3T 1C5, Canada
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15
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Alvarez-Curto E, Inoue A, Jenkins L, Raihan SZ, Prihandoko R, Tobin AB, Milligan G. Targeted Elimination of G Proteins and Arrestins Defines Their Specific Contributions to Both Intensity and Duration of G Protein-coupled Receptor Signaling. J Biol Chem 2016; 291:27147-27159. [PMID: 27852822 PMCID: PMC5207144 DOI: 10.1074/jbc.m116.754887] [Citation(s) in RCA: 131] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Revised: 11/14/2016] [Indexed: 12/29/2022] Open
Abstract
G protein-coupled receptors (GPCRs) can initiate intracellular signaling cascades by coupling to an array of heterotrimeric G proteins and arrestin adaptor proteins. Understanding the contribution of each of these coupling options to GPCR signaling has been hampered by a paucity of tools to selectively perturb receptor function. Here we employ CRISPR/Cas9 genome editing to eliminate selected G proteins (Gαq and Gα11) or arrestin2 and arrestin3 from HEK293 cells together with the elimination of receptor phosphorylation sites to define the relative contribution of G proteins, arrestins, and receptor phosphorylation to the signaling outcomes of the free fatty acid receptor 4 (FFA4). A lack of FFA4-mediated elevation of intracellular Ca2+ in Gαq/Gα11-null cells and agonist-mediated receptor internalization in arrestin2/3-null cells confirmed previously reported canonical signaling features of this receptor, thereby validating the genome-edited HEK293 cells. FFA4-mediated ERK1/2 activation was totally dependent on Gq/11 but intriguingly was substantially enhanced for FFA4 receptors lacking sites of regulated phosphorylation. This was not due to a simple lack of desensitization of Gq/11 signaling because the Gq/11-dependent calcium response was desensitized by both receptor phosphorylation and arrestin-dependent mechanisms, whereas a substantially enhanced ERK1/2 response was only observed for receptors lacking phosphorylation sites and not in arrestin2/3-null cells. In conclusion, we validate CRISPR/Cas9 engineered HEK293 cells lacking Gq/11 or arrestin2/3 as systems for GPCR signaling research and employ these cells to reveal a previously unappreciated interplay of signaling pathways where receptor phosphorylation can impact on ERK1/2 signaling through a mechanism that is likely independent of arrestins.
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Affiliation(s)
- Elisa Alvarez-Curto
- From the Centre for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom,
| | - Asuka Inoue
- the Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Miyagi 980-8578, Japan, and.,the Japan Science and Technology Agency (JST), Precursory Research for Embryonic Science and Technology (PRESTO), Kawaguchi, Saitama 332-0012, Japan
| | - Laura Jenkins
- From the Centre for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom
| | - Sheikh Zahir Raihan
- From the Centre for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom
| | - Rudi Prihandoko
- From the Centre for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom
| | - Andrew B Tobin
- From the Centre for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom
| | - Graeme Milligan
- From the Centre for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom,
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Kulyk VB, Chyzhmakov IV, Volkova TM, Kryshtal OA. Ambivalent Effects on P2X3 Receptors in Rat Sensory Neurons in the Presence of Opioid Receptor Antagonists. NEUROPHYSIOLOGY+ 2015. [DOI: 10.1007/s11062-015-9519-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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17
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Canals M. The Complex Roles of μ-Opioid Receptor Phosphorylation: A Key Determinant in Receptor Signaling and Regulation. Mol Pharmacol 2015; 88:814-5. [PMID: 26152197 DOI: 10.1124/mol.115.100180] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Accepted: 07/07/2015] [Indexed: 11/22/2022] Open
Abstract
This Commentary focuses on two articles in the October 2015 issue of Molecular Pharmacology that investigate the role of μ-opioid receptor phosphorylation in receptor agonist binding and desensitization. The work of Birdsong et al. and Yousuf et al. clearly highlights the complexity that researchers face when trying to assess the signaling and regulatory consequences of G protein-coupled receptor phosphorylation.
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Affiliation(s)
- Meritxell Canals
- Drug Discovery Biology Theme and ARC Center of Excellence in Convergent Bio-Nano Science and Technology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
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18
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Birdsong WT, Arttamangkul S, Bunzow JR, Williams JT. Agonist Binding and Desensitization of the μ-Opioid Receptor Is Modulated by Phosphorylation of the C-Terminal Tail Domain. Mol Pharmacol 2015; 88:816-24. [PMID: 25934731 DOI: 10.1124/mol.114.097527] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Accepted: 04/30/2015] [Indexed: 11/22/2022] Open
Abstract
Sustained activation of G protein-coupled receptors can lead to a rapid decline in signaling through acute receptor desensitization. In the case of the μ-opioid receptor (MOPr), this desensitization may play a role in the development of analgesic tolerance. It is understood that phosphorylation of MOPr promotes association with β-arrestin proteins, which then facilitates desensitization and receptor internalization. Agonists that induce acute desensitization have been shown to induce a noncanonical high-affinity agonist binding state in MOPr, conferring a persistent memory of prior receptor activation. In the current study, live-cell confocal imaging was used to investigate the role of receptor phosphorylation in agonist binding to MOPr. A phosphorylation cluster in the C-terminal tail of MOPr was identified as a mediator of agonist-induced affinity changes in MOPr. This site is unique from the primary phosphorylation cluster responsible for β-arrestin binding and internalization. Electrophysiologic measurements of receptor function suggest that both phosphorylation clusters may play a parallel role during acute receptor desensitization. Desensitization was unaffected by alanine mutation of either phosphorylation cluster, but was largely eliminated when both clusters were mutated. Overall, this work suggests that there are multiple effects of MOPr phosphorylation that appear to regulate MOPr function: one affecting β-arrestin binding and a second affecting agonist binding.
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Affiliation(s)
| | | | - James R Bunzow
- Vollum Institute, Oregon Health & Science University, Portland, Oregon
| | - John T Williams
- Vollum Institute, Oregon Health & Science University, Portland, Oregon
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19
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Abstract
Medication-assisted treatment of opioid use disorder with physiological dependence at least doubles rates of opioid-abstinence outcomes in randomized, controlled trials comparing psychosocial treatment of opioid use disorder with medication versus with placebo or no medication. This article reviews the current evidence for medication-assisted treatment of opioid use disorder and also presents clinical practice imperatives for preventing opioid overdose and the transmission of infectious disease. The evidence strongly supports the use of agonist therapies to reduce opioid use and to retain patients in treatment, with methadone maintenance remaining the gold standard of care. Combined buprenorphine/naloxone, however, also demonstrates significant efficacy and favorable safety and tolerability in multiple populations, including youth and prescription opioid-dependent individuals, as does buprenorphine monotherapy in pregnant women. The evidence for antagonist therapies is weak. Oral naltrexone demonstrates poor adherence and increased mortality rates, although the early evidence looks more favorable for extended-release naltrexone, which has the advantages that it is not subject to misuse or diversion and that it does not present a risk of overdose on its own. Two perspectives-individualized treatment and population management-are presented for selecting among the three available Food and Drug Administration-approved maintenance therapies for opioid use disorder. The currently unmet challenges in treating opioid use disorder are discussed, as are the directions for future research.
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20
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Chizhmakov I, Kulyk V, Khasabova I, Khasabov S, Simone D, Bakalkin G, Gordienko D, Verkhratsky A, Krishtal O. Molecular mechanism for opioid dichotomy: bidirectional effect of μ-opioid receptors on P2X₃ receptor currents in rat sensory neurones. Purinergic Signal 2015; 11:171-81. [PMID: 25592684 DOI: 10.1007/s11302-015-9443-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Accepted: 01/05/2015] [Indexed: 12/28/2022] Open
Abstract
Here, we describe a molecular switch associated with opioid receptors-linked signalling cascades that provides a dual opioid control over P2X3 purinoceptor in sensory neurones. Leu-enkephalin inhibited P2X3-mediated currents with IC50 ~10 nM in ~25% of small nociceptive rat dorsal root ganglion (DRG) neurones. In contrast, in neurones pretreated with pertussis toxin leu-enkephalin produced stable and significant increase of P2X3 currents. All effects of opioid were abolished by selective μ-opioid receptor antagonist D-Phe-Cys-Tyr-D-Trp-Orn-Thr-Pen-Thr-NH2 (CTOP), nonselective inhibitor naloxone, and by PLC inhibitor U73122. Thus, we discovered a dual link between purinoceptors and μ-opioid receptors: the latter exert both inhibitory (pertussis toxin-sensitive) and stimulatory (pertussis toxin-insensitive) actions on P2X3 receptors through phospholipase C (PLC)-dependent pathways. This dual opioid control of P2X3 receptors may provide a molecular explanation for dichotomy of opioid therapy. Pharmacological control of this newly identified facilitation/inhibition switch may open new perspectives for the adequate medical use of opioids, the most powerful pain-killing agents known today.
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Affiliation(s)
- Igor Chizhmakov
- State Key Laboratory for Molecular Biology, Bogomoletz Institute of Physiology, 4 Bogomoletz str., Kiev, 01024, Ukraine
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21
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Arttamangkul S, Birdsong W, Williams JT. Does PKC activation increase the homologous desensitization of μ opioid receptors? Br J Pharmacol 2015; 172:583-92. [PMID: 24697621 PMCID: PMC4292970 DOI: 10.1111/bph.12712] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Revised: 03/19/2014] [Accepted: 03/23/2014] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND AND PURPOSE This study examined the role of agents known to activate PKC on morphine-induced desensitization of μ-opioid receptors (MOP receptors) in brain slices containing locus coeruleus neurons. EXPERIMENTAL APPROACH Intracellular recordings were obtained from rat locus coeruleus neurons. Two measurements were used to characterize desensitization, the decline in hyperpolarization induced by application of a saturating concentration of agonist (acute desensitization) and the decrease in hyperpolarization induced by a subsaturating concentration of [Met](5) enkephalin (ME) following washout of the saturating concentration (sustained desensitization). Internalization of MOP receptors was studied in brain slices prepared from transgenic mice expressing Flag-MOP receptors. The subcellular distribution of activated PKC was examined using a novel fluorescent sensor of PKC in HEK293 cells. KEY RESULTS The phorbol esters (PMA and PDBu) and muscarine increased acute desensitization induced by a saturating concentration of morphine and ME. These effects were not sensitive to staurosporine. Staurosporine did not block the decline in hyperpolarization induced by muscarine. PDBu and muscarine did not affect sustained desensitization induced by ME nor did phorbol esters or muscarine change the trafficking of MOP receptors induced by morphine or ME. The distribution of activated PKC measured in HEK293 cells differed depending on which phorbol ester was applied. CONCLUSIONS AND IMPLICATIONS This study demonstrates a distinct difference in two measurements that are often used to evaluate desensitization. The measure of decline correlated well with the reduction in peak amplitudes caused by PKC activators implicating the modification of other factors rather than MOP receptors. LINKED ARTICLES This article is part of a themed section on Opioids: New Pathways to Functional Selectivity. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2015.172.issue-2.
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Abstract
This paper is the thirty-sixth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2013 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; alcohol and drugs of abuse; 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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23
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Williams JT. Desensitization of functional µ-opioid receptors increases agonist off-rate. Mol Pharmacol 2014; 86:52-61. [PMID: 24748657 PMCID: PMC4054003 DOI: 10.1124/mol.114.092098] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2014] [Accepted: 04/17/2014] [Indexed: 11/22/2022] Open
Abstract
Desensitization of µ-opioid receptors (MORs) develops over 5-15 minutes after the application of some, but not all, opioid agonists and lasts for tens of minutes after agonist removal. The decrease in function is receptor selective (homologous) and could result from 1) a reduction in receptor number or 2) a decrease in receptor coupling. The present investigation used photolysis of two caged opioid ligands to examine the kinetics of MOR-induced potassium conductance before and after MOR desensitization. Photolysis of a caged antagonist, carboxynitroveratryl-naloxone (caged naloxone), blocked the current induced by a series of agonists, and the time constant of decline was significantly decreased after desensitization. The increase in the rate of current decay was not observed after partial blockade of receptors with the irreversible antagonist, β-chlornaltrexamine (β-CNA). The time constant of current decay after desensitization was never more rapid than 1 second, suggesting an increased agonist off-rate rather than an increase in the rate of channel closure downstream of the receptor. The rate of G protein-coupled K(+) channel (GIRK) current activation was examined using photolysis of a caged agonist, carboxynitrobenzyl-tyrosine-[Leu(5)]-enkephalin. After acute desensitization or partial irreversible block of MORs with β-CNA, there was an increase in the time it took to reach a peak current. The decrease in the rate of agonist-induced GIRK conductance was receptor selective and dependent on receptor number. The results indicate that opioid receptor desensitization reduced the number of functional receptor and that the remaining active receptors have a reduced agonist affinity.
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Affiliation(s)
- John T Williams
- Vollum Institute, Oregon Health and Science University, Portland, Oregon
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24
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Macey TA, Bobeck EN, Suchland KL, Morgan MM, Ingram SL. Change in functional selectivity of morphine with the development of antinociceptive tolerance. Br J Pharmacol 2014; 172:549-61. [PMID: 24666417 DOI: 10.1111/bph.12703] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Revised: 03/14/2014] [Accepted: 03/18/2014] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND AND PURPOSE Opioids, such as morphine, are the most effective treatment for pain but their efficacy is diminished with the development of tolerance following repeated administration. Recently, we found that morphine activated ERK in opioid-tolerant but not in naïve rats, suggesting that morphine activation of μ-opioid receptors is altered following repeated morphine administration. Here, we have tested the hypothesis that μ-opioid receptor activation of ERK in the ventrolateral periaqueductal gray (vlPAG) is dependent on dynamin, a protein implicated in receptor endocytosis. EXPERIMENTAL APPROACH Rats were made tolerant to repeated microinjections of morphine into the vlPAG. The effects of dynamin on ERK activation and antinociception were assessed by microinjecting myristoylated dominant-negative dynamin peptide (Dyn-DN) or a scrambled control peptide into the vlPAG. Microinjection of a fluorescent dermorphin analogue (DERM-A594) into the vlPAG was used to monitor μ-opioid receptor internalization. KEY RESULTS Morphine did not activate ERK and Dyn-DN administration had no effect on morphine-induced antinociception in saline-pretreated rats. In contrast, morphine-induced ERK activation in morphine-pretreated rats that was blocked by Dyn-DN administration. Dyn-DN also inhibited morphine antinociception. Finally, morphine reduced DERM-A594 internalization only in morphine-tolerant rats indicating that μ-opioid receptors were internalized and unavailable to bind DERM-A594. CONCLUSIONS AND IMPLICATIONS Repeated morphine administration increased μ-opioid receptor activation of ERK signalling via a dynamin-dependent mechanism. These results demonstrate that the balance of agonist signalling to G-protein and dynamin-dependent pathways is altered, effectively changing the functional selectivity of the agonist-receptor complex. LINKED ARTICLES This article is part of a themed section on Opioids: New Pathways to Functional Selectivity. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2015.172.issue-2.
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Affiliation(s)
- T A Macey
- Department of Neurological Surgery, Oregon Health & Science University, Portland, OR, USA
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25
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Jaremko KM, Thompson NL, Reyes BAS, Jin J, Ebersole B, Jenney CB, Grigson PS, Levenson R, Berrettini WH, Van Bockstaele EJ. Morphine-induced trafficking of a mu-opioid receptor interacting protein in rat locus coeruleus neurons. Prog Neuropsychopharmacol Biol Psychiatry 2014; 50:53-65. [PMID: 24333843 PMCID: PMC3928604 DOI: 10.1016/j.pnpbp.2013.12.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Revised: 11/26/2013] [Accepted: 12/05/2013] [Indexed: 12/14/2022]
Abstract
Opiate addiction is a devastating health problem, with approximately 2million people currently addicted to heroin or non-medical prescription opiates in the United States alone. In neurons, adaptations in cell signaling cascades develop following opioid actions at the mu opioid receptor (MOR). A novel putative target for intervention involves interacting proteins that may regulate trafficking of MOR. Morphine has been shown to induce a re-distribution of a MOR-interacting protein Wntless (WLS, a transport molecule necessary for secretion of neurotrophic Wnt proteins), from cytoplasmic to membrane compartments in rat striatal neurons. Given its opiate-sensitivity and its well-characterized molecular and cellular adaptations to morphine exposure, we investigated the anatomical distribution of WLS and MOR in the rat locus coeruleus (LC)-norepinephrine (NE) system. Dual immunofluorescence microscopy was used to test the hypothesis that WLS is localized to noradrenergic neurons of the LC and that WLS and MOR co-exist in common LC somatodendritic processes, providing an anatomical substrate for their putative interactions. We also hypothesized that morphine would influence WLS distribution in the LC. Rats received saline, morphine or the opiate agonist [d-Ala2, N-Me-Phe4, Gly-ol5]-enkephalin (DAMGO), and tissue sections through the LC were processed for immunogold-silver detection of WLS and MOR. Statistical analysis showed a significant re-distribution of WLS to the plasma membrane following morphine treatment in addition to an increase in the proximity of gold-silver labels for MOR and WLS. Following DAMGO treatment, MOR and WLS were predominantly localized within the cytoplasmic compartment when compared to morphine and control. In a separate cohort of rats, brains were obtained from saline-treated or heroin self-administering male rats for pulldown co-immunoprecipitation studies. Results showed an increased association of WLS and MOR following heroin exposure. As the LC-NE system is important for cognition as well as decisions underlying substance abuse, adaptations in WLS trafficking and expression may play a role in modulating MOR function in the LC and contribute to the negative sequelae of opiate exposure on executive function.
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Affiliation(s)
- Kellie M Jaremko
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA 19102, United States
| | - Nicholas L Thompson
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA 19102, United States
| | - Beverly A S Reyes
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA 19102, United States.
| | - Jay Jin
- Department of Pharmacology, Penn State College of Medicine, Hershey, PA 17033, United States
| | - Brittany Ebersole
- Department of Pharmacology, Penn State College of Medicine, Hershey, PA 17033, United States
| | - Christopher B Jenney
- Department of Neural and Behavioral Sciences, Penn State College of Medicine, Hershey, PA 17033, United States
| | - Patricia S Grigson
- Department of Neural and Behavioral Sciences, Penn State College of Medicine, Hershey, PA 17033, United States
| | - Robert Levenson
- Department of Pharmacology, Penn State College of Medicine, Hershey, PA 17033, United States
| | - Wade H Berrettini
- Department of Psychiatry, Center for Neurobiology and Behavior, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, United States
| | - Elisabeth J Van Bockstaele
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA 19102, United States
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Kupchik YM, Scofield MD, Rice KC, Cheng K, Roques BP, Kalivas PW. Cocaine dysregulates opioid gating of GABA neurotransmission in the ventral pallidum. J Neurosci 2014; 34:1057-66. [PMID: 24431463 PMCID: PMC3891949 DOI: 10.1523/jneurosci.4336-13.2014] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2013] [Revised: 11/12/2013] [Accepted: 12/04/2013] [Indexed: 11/21/2022] Open
Abstract
The ventral pallidum (VP) is a target of dense nucleus accumbens projections. Many of these projections coexpress GABA and the neuropeptide enkephalin, a δ and μ opioid receptor (MOR) ligand. Of these two, the MOR in the VP is known to be involved in reward-related behaviors, such as hedonic responses to palatable food, alcohol intake, and reinstatement of cocaine seeking. Stimulating MORs in the VP decreases extracellular GABA, indicating that the effects of MORs in the VP on cocaine seeking are via modulating GABA neurotransmission. Here, we use whole-cell patch-clamp on a rat model of withdrawal from cocaine self-administration to test the hypothesis that MORs presynaptically regulate GABA transmission in the VP and that cocaine withdrawal changes the interaction between MORs and GABA. We found that in cocaine-extinguished rats pharmacological activation of MORs no longer presynaptically inhibited GABA release, whereas blocking the MORs disinhibited GABA release. Moreover, MOR-dependent long-term depression of GABA neurotransmission in the VP was lost in cocaine-extinguished rats. Last, GABA neurotransmission was found to be tonically suppressed in cocaine-extinguished rats. These substantial synaptic changes indicated that cocaine was increasing tone on MOR receptors. Accordingly, increasing endogenous tone by blocking the enzymatic degradation of enkephalin inhibited GABA neurotransmission in yoked saline rats but not in cocaine-extinguished rats. In conclusion, our results indicate that following withdrawal from cocaine self-administration enkephalin levels in the VP are elevated and the opioid modulation of GABA neurotransmission is impaired. This may contribute to the difficulties withdrawn addicts experience when trying to resist relapse.
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Affiliation(s)
- Yonatan M Kupchik
- Department of Neurosciences, Medical University of South Carolina, Charleston, South Carolina 29425, Chemical Biology Research Branch, National Institute on Drug Abuse and National Institute on Alcohol and Alcoholism, Rockville, Maryland 20892, Pharmaleads SAS, 75013 Paris, France, and Université Paris-Descartes, 75006 Paris, France
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Nickolls SA, Humphreys S, Clark M, McMurray G. Co-expression of GRK2 reveals a novel conformational state of the µ-opioid receptor. PLoS One 2013; 8:e83691. [PMID: 24376730 PMCID: PMC3869807 DOI: 10.1371/journal.pone.0083691] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2013] [Accepted: 11/15/2013] [Indexed: 11/19/2022] Open
Abstract
Agonists at the µ-opioid receptor are known to produce potent analgesic responses in the clinical setting, therefore, an increased understanding of the molecular interactions of ligands at this receptor could lead to improved analgesics. As historically morphine has been shown to be a poor recruiter of β-arrestin in recombinant cell systems and this can be overcome by the co-expression of GRK2, we investigated the effects of GRK2 co-expression, in a recombinant µ-opioid receptor cell line, on ligand affinity and intrinsic activity in both β-arrestin recruitment and [(35)S]GTPγS binding assays. We also investigated the effect of receptor depletion in the β-arrestin assay. GRK2 co-expression increased both agonist Emax and potency in the β-arrestin assay. The increase in agonist potency could not be reversed using receptor depletion, supporting that the effects were due to a novel receptor conformation not system amplification. We also observed a small but significant effect on agonist KL values. Potency values in the [(35)S]GTPγS assay were unchanged; however, inverse agonist activity became evident with GRK2 co-expression. We conclude that this is direct evidence that the µ-opioid receptor is an allosteric protein and the co-expression of signalling molecules elicits changes in its conformation and thus ligand affinity. This has implications when describing how ligands interact with the receptor and how efficacy is determined.
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Affiliation(s)
- Sarah A. Nickolls
- Neusentis, A Pfizer Research Unit, Granta Park, Cambridge, United Kingdom
- * E-mail:
| | - Sian Humphreys
- Neusentis, A Pfizer Research Unit, Granta Park, Cambridge, United Kingdom
| | - Mellissa Clark
- Neusentis, A Pfizer Research Unit, Granta Park, Cambridge, United Kingdom
| | - Gordon McMurray
- Neusentis, A Pfizer Research Unit, Granta Park, Cambridge, United Kingdom
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Li G, Ma F, Gu Y, Huang LYM. Analgesic tolerance of opioid agonists in mutant mu-opioid receptors expressed in sensory neurons following intrathecal plasmid gene delivery. Mol Pain 2013; 9:63. [PMID: 24304623 PMCID: PMC3906983 DOI: 10.1186/1744-8069-9-63] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Accepted: 11/22/2013] [Indexed: 11/12/2022] Open
Abstract
Background Phosphorylation sites in the C-terminus of mu-opioid receptors (MORs) are known to play critical roles in the receptor functions. Our understanding of their participation in opioid analgesia is mostly based on studies of opioid effects on mutant receptors expressed in in vitro preparations, including cell lines, isolated neurons and brain slices. The behavioral consequences of the mutation have not been fully explored due to the complexity in studies of mutant receptors in vivo. To facilitate the determination of the contribution of phosphorylation sites in MOR to opioid-induced analgesic behaviors, we expressed mutant and wild-type human MORs (hMORs) in sensory dorsal root ganglion (DRG) neurons, a major site for nociceptive (pain) signaling and determined morphine- and the full MOR agonist, DAMGO,-induced effects on heat-induced hyperalgesic behaviors and potassium current (IK) desensitization in these rats. Findings A mutant hMOR DNA with the putative phosphorylation threonine site at position 394 replaced by an alanine (T394A), i.e., hMOR-T, or a plasmid containing wild type hMOR (as a positive control) was intrathecally delivered. The plasmid containing GFP or saline was used as the negative control. To limit the expression of exogenous DNA to neurons of DRGs, a neuron-specific promoter was included in the plasmid. Following a plasmid injection, hMOR-T or hMOR receptors were expressed in small and medium DRG neurons. Compared with saline or GFP rats, the analgesic potency of morphine was increased to a similar extent in hMOR-T and hMOR rats. Morphine induced minimum IK desensitization in both rat groups. In contrast, DAMGO increased analgesic potency and elicited IK desensitization to a significantly less extent in hMOR-T than in hMOR rats. The development and extent of acute and chronic tolerance induced by repeated morphine or DAMGO applications were not altered by the T394A mutation. Conclusions These results indicate that phosphorylation of T394 plays a critical role in determining the potency of DAMGO-induced analgesia and IK desensitization, but has limited effect on morphine-induced responses. On the other hand, the mutation contributes minimally to both DAMGO- and morphine-induced behavioral tolerance. Furthermore, the study shows that plasmid gene delivery of mutant receptors to DRG neurons is a useful strategy to explore nociceptive behavioral consequences of the mutation.
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Affiliation(s)
- Guangwen Li
- Department of Neuroscience and Cell Biology, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555-1069, USA.
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Banghart MR, Williams JT, Shah RC, Lavis LD, Sabatini BL. Caged naloxone reveals opioid signaling deactivation kinetics. Mol Pharmacol 2013; 84:687-95. [PMID: 23960100 DOI: 10.1124/mol.113.088096] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The spatiotemporal dynamics of opioid signaling in the brain remain poorly defined. Photoactivatable opioid ligands provide a means to quantitatively measure these dynamics and their underlying mechanisms in brain tissue. Although activation kinetics can be assessed using caged agonists, deactivation kinetics are obscured by slow clearance of agonist in tissue. To reveal deactivation kinetics of opioid signaling we developed a caged competitive antagonist that can be quickly photoreleased in sufficient concentrations to render agonist dissociation effectively irreversible. Carboxynitroveratryl-naloxone (CNV-NLX), a caged analog of the competitive opioid antagonist NLX, was readily synthesized from commercially available NLX in good yield and found to be devoid of antagonist activity at heterologously expressed opioid receptors. Photolysis in slices of rat locus coeruleus produced a rapid inhibition of the ionic currents evoked by multiple agonists of the μ-opioid receptor (MOR), but not of α-adrenergic receptors, which activate the same pool of ion channels. Using the high-affinity peptide agonist dermorphin, we established conditions under which light-driven deactivation rates are independent of agonist concentration and thus intrinsic to the agonist-receptor complex. Under these conditions, some MOR agonists yielded deactivation rates that are limited by G protein signaling, whereas others appeared limited by agonist dissociation. Therefore, the choice of agonist determines which feature of receptor signaling is unmasked by CNV-NLX photolysis.
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Affiliation(s)
- Matthew R Banghart
- Howard Hughes Medical Institute, Department of Neurobiology, Harvard Medical School, Boston, Massachusetts (M.R.B., R.C.S., B.L.S.); Vollum Institute, Oregon Health & Science University, Portland, Oregon (J.T.W.); and Janelia Farm Research Campus, Howard Hughes Medical Institute, Ashburn, Virginia (L.D.L.)
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