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Sharma S, Naldrett MJ, Gill MJ, Checco JW. Affinity-Driven Aryl Diazonium Labeling of Peptide Receptors on Living Cells. J Am Chem Soc 2024; 146:13676-13688. [PMID: 38693710 PMCID: PMC11149697 DOI: 10.1021/jacs.4c04672] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/03/2024]
Abstract
Peptide-receptor interactions play critical roles in a wide variety of physiological processes. Methods to link bioactive peptides covalently to unmodified receptors on the surfaces of living cells are valuable for studying receptor signaling, dynamics, and trafficking and for identifying novel peptide-receptor interactions. Here, we utilize peptide analogues bearing deactivated aryl diazonium groups for the affinity-driven labeling of unmodified receptors. We demonstrate that aryl diazonium-bearing peptide analogues can covalently label receptors on the surface of living cells using both the neurotensin and the glucagon-like peptide 1 receptor systems. Receptor labeling occurs in the complex environment of the cell surface in a sequence-specific manner. We further demonstrate the utility of this covalent labeling approach for the visualization of peptide receptors by confocal fluorescence microscopy and for the enrichment and identification of labeled receptors by mass spectrometry-based proteomics. Aryl diazonium-based affinity-driven receptor labeling is attractive due to the high abundance of tyrosine and histidine residues susceptible to azo coupling in the peptide binding sites of receptors, the ease of incorporation of aryl diazonium groups into peptides, and the relatively small size of the aryl diazonium group. This approach should prove to be a powerful and relatively general method to study peptide-receptor interactions in cellular contexts.
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Affiliation(s)
- Sheryl Sharma
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, United States
- The Nebraska Center for Integrated Biomolecular Communication (NCIBC), University of Nebraska-Lincoln, Lincoln, Nebraska 68588, United States
| | - Michael J Naldrett
- Proteomics and Metabolomics Facility, Nebraska Center for Biotechnology, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, United States
| | - Makayla J Gill
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, United States
| | - James W Checco
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, United States
- The Nebraska Center for Integrated Biomolecular Communication (NCIBC), University of Nebraska-Lincoln, Lincoln, Nebraska 68588, United States
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Hohenwarter L, Böttger R, Li SD. Modification and Delivery of Enkephalins for Pain Modulation. Int J Pharm 2023; 646:123425. [PMID: 37739096 DOI: 10.1016/j.ijpharm.2023.123425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Revised: 08/23/2023] [Accepted: 09/15/2023] [Indexed: 09/24/2023]
Abstract
Chronic pain negatively affects patient's quality of life and poses a significant economic burden. First line pharmaceutical treatment of chronic pain, including NSAIDs or antidepressants, is often inefficient to reduce pain, or produces intolerable adverse effects. In such cases, opioids are frequently prescribed for their potent analgesia, but chronic opioid use is also frequently associated with debilitating side effects that may offset analgesic benefits. Nonetheless, opioids continue to be widely utilized due to the lack of effective alternative analgesics. Since their discovery in 1975, a class of endogenous opioids called enkephalins (ENKs) have been investigated for their ability to relieve pain with significantly reduced adverse effects compared to conventional opioids. Their low metabolic stability and inability to cross biological membranes, however, make ENKs ineffective analgesics. Over past decades, much effort has been invested to overcome these limitations and develop ENK-based pain therapies. This review summarizes and describes chemical modifications and ENK delivery technologies utilizing ENK conjugates, nanoparticles and ENK gene delivery approaches and discusses valid lessons, challenges, and future directions of this evolving field.
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Affiliation(s)
- Lukas Hohenwarter
- Faculty of Pharmaceutical Sciences, The University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Roland Böttger
- Faculty of Pharmaceutical Sciences, The University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Shyh-Dar Li
- Faculty of Pharmaceutical Sciences, The University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada.
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3
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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] [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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Mack SM, Gomes I, Fakira AK, Duarte ML, Gupta A, Fricker L, Devi LA. GPR83 engages endogenous peptides from two distinct precursors to elicit differential signaling. Mol Pharmacol 2022; 102:MOLPHARM-AR-2022-000487. [PMID: 35605991 PMCID: PMC9341263 DOI: 10.1124/molpharm.122.000487] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Revised: 04/28/2022] [Accepted: 05/03/2022] [Indexed: 09/11/2023] Open
Abstract
PEN is an abundant neuropeptide that activates GPR83, a G protein-coupled receptor that is considered a novel therapeutic target due to its roles in regulation of feeding, reward, and anxiety-related behaviors. The major form of PEN in the brain is 22 residues in length. Previous studies have identified shorter forms of PEN in mouse brain and neuroendocrine cells; these shorter forms were named PEN18, PEN19 and PEN20, with the number reflecting the length of the peptide. The C-terminal five residues of PEN20 are identical to the C-terminus of a procholecystokinin (proCCK)-derived peptide, named proCCK56-62, that is present in mouse brain. ProCCK56-62 is highly conserved across species although it has no homology to the bioactive cholecystokinin domain. ProCCK56-62 and a longer form, proCCK56-63 were tested for their ability to engage GPR83. Both peptides bind GPR83 with high affinity, activate second messenger pathways, and induce ligand-mediated receptor endocytosis. Interestingly, the shorter PEN peptides, ProCC56-62, and ProCCK56-63 differentially activate signal transduction pathways. Whereas PEN22 and PEN20 facilitate receptor coupling to Gai, PEN18, PEN19 and ProCCK peptides facilitate coupling to Gas. Furthermore, the ProCCK peptides exhibit dose dependent Ga subtype selectivity in that they faciliate coupling to Gas at low concentrations and Gai at high concentrations. These data demonstrate that peptides derived from two distinct peptide precursors can differentially activate GPR83, and that GPR83 exhibits Ga subtype preference depending on the nature and concentration of the peptide. These results are consistent with the emerging idea that endogenous neuropeptides function as biased ligands. Significance Statement We found that peptides derived from proCCK bind and activate GPR83, a G protein-coupled receptor that is known to bind peptides derived from proSAAS. Different forms of the proCCK- and proSAAS-derived peptides show biased agonism, activating Gas or Gai depending on the length of the peptide and/or its concentration.
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Affiliation(s)
- Seshat M Mack
- Department of Pharmacological Sciences, Mount Sinai School of Medicine, United States
| | - Ivone Gomes
- Department of Pharmacology & Systems Therapeutics, Mount Sinai School of Medicine, United States
| | - Amanda K Fakira
- Department of Biomedical Sciences, Cooper Medical School of Rowan University, United States
| | - Mariana L Duarte
- Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, United States
| | - Achla Gupta
- Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, United States
| | - Lloyd Fricker
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, United States
| | - Lakshmi A Devi
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, United States
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Fricker LD, Margolis EB, Gomes I, Devi LA. Five Decades of Research on Opioid Peptides: Current Knowledge and Unanswered Questions. Mol Pharmacol 2020; 98:96-108. [PMID: 32487735 DOI: 10.1124/mol.120.119388] [Citation(s) in RCA: 74] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2020] [Accepted: 05/06/2020] [Indexed: 12/20/2022] Open
Abstract
In the mid-1970s, an intense race to identify endogenous substances that activated the same receptors as opiates resulted in the identification of the first endogenous opioid peptides. Since then, >20 peptides with opioid receptor activity have been discovered, all of which are generated from three precursors, proenkephalin, prodynorphin, and proopiomelanocortin, by sequential proteolytic processing by prohormone convertases and carboxypeptidase E. Each of these peptides binds to all three of the opioid receptor types (μ, δ, or κ), albeit with differing affinities. Peptides derived from proenkephalin and prodynorphin are broadly distributed in the brain, and mRNA encoding all three precursors are highly expressed in some peripheral tissues. Various approaches have been used to explore the functions of the opioid peptides in specific behaviors and brain circuits. These methods include directly administering the peptides ex vivo (i.e., to excised tissue) or in vivo (in animals), using antagonists of opioid receptors to infer endogenous peptide activity, and genetic knockout of opioid peptide precursors. Collectively, these studies add to our current understanding of the function of endogenous opioids, especially when similar results are found using different approaches. We briefly review the history of identification of opioid peptides, highlight the major findings, address several myths that are widely accepted but not supported by recent data, and discuss unanswered questions and future directions for research. SIGNIFICANCE STATEMENT: Activation of the opioid receptors by opiates and synthetic drugs leads to central and peripheral biological effects, including analgesia and respiratory depression, but these may not be the primary functions of the endogenous opioid peptides. Instead, the opioid peptides play complex and overlapping roles in a variety of systems, including reward pathways, and an important direction for research is the delineation of the role of individual peptides.
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Affiliation(s)
- Lloyd D Fricker
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York (L.D.F.); Department of Neurology, UCSF Weill Institute for Neurosciences, San Francisco, California (E.B.M.); and Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, New York (I.G., L.A.D.)
| | - Elyssa B Margolis
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York (L.D.F.); Department of Neurology, UCSF Weill Institute for Neurosciences, San Francisco, California (E.B.M.); and Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, New York (I.G., L.A.D.)
| | - Ivone Gomes
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York (L.D.F.); Department of Neurology, UCSF Weill Institute for Neurosciences, San Francisco, California (E.B.M.); and Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, New York (I.G., L.A.D.)
| | - Lakshmi A Devi
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York (L.D.F.); Department of Neurology, UCSF Weill Institute for Neurosciences, San Francisco, California (E.B.M.); and Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, New York (I.G., L.A.D.)
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6
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Bagheri Tudashki H, Haddad Y, Charfi I, Couture R, Pineyro G. Ligand-specific recycling profiles determine distinct potential for chronic analgesic tolerance of delta-opioid receptor (DOPr) agonists. J Cell Mol Med 2020; 24:5718-5730. [PMID: 32279433 PMCID: PMC7214178 DOI: 10.1111/jcmm.15234] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Revised: 03/11/2020] [Accepted: 03/12/2020] [Indexed: 12/25/2022] Open
Abstract
δ-opioid receptor (DOPr) agonists have analgesic efficacy in chronic pain models but development of tolerance limits their use for long-term pain management. Although agonist potential for inducing acute analgesic tolerance has been associated with distinct patterns of DOPr internalization, the association between trafficking and chronic tolerance remains ill-defined. In a rat model of streptozotocin (STZ)-induced diabetic neuropathy, deltorphin II and TIPP produced sustained analgesia following daily (intrathecal) i.t. injections over six days, whereas similar treatment with SNC-80 or SB235863 led to progressive tolerance and loss of the analgesic response. Trafficking assays in murine neuron cultures showed no association between the magnitude of ligand-induced sequestration and development of chronic tolerance. Instead, ligands that supported DOPr recycling were also the ones producing sustained analgesia over 6-day treatment. Moreover, endosomal endothelin-converting enzyme 2 (ECE2) blocker 663444 prevented DOPr recycling by deltorphin II and TIPP and precipitated tolerance by these ligands. In conclusion, agonists, which support DOPr recycling, avoid development of analgesic tolerance over repeated administration.
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Affiliation(s)
| | - Youssef Haddad
- Department of Pharmacology and PhysiologyFaculty of MedicineUniversité de MontréalMontréalQCCanada
| | - Iness Charfi
- Centre de RechercheCentre Hospitalier Universitaire Ste-JustineMontréalQCCanada
- Department of Pharmacology and PhysiologyFaculty of MedicineUniversité de MontréalMontréalQCCanada
| | - Rejean Couture
- Department of Pharmacology and PhysiologyFaculty of MedicineUniversité de MontréalMontréalQCCanada
| | - Graciela Pineyro
- Centre de RechercheCentre Hospitalier Universitaire Ste-JustineMontréalQCCanada
- Department of Pharmacology and PhysiologyFaculty of MedicineUniversité de MontréalMontréalQCCanada
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7
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Lobingier BT, von Zastrow M. When trafficking and signaling mix: How subcellular location shapes G protein-coupled receptor activation of heterotrimeric G proteins. Traffic 2019; 20:130-136. [PMID: 30578610 DOI: 10.1111/tra.12634] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Revised: 12/19/2018] [Accepted: 12/20/2018] [Indexed: 12/14/2022]
Abstract
G protein-coupled receptors (GPCRs) physically connect extracellular information with intracellular signal propagation. Membrane trafficking plays a supportive role by "bookending" signaling events: movement through the secretory pathway delivers GPCRs to the cell surface where receptors can sample the extracellular environment, while endocytosis and endolysosomal membrane trafficking provide a versatile system to titrate cellular signaling potential and maintain homeostatic control. Recent evidence suggests that, in addition to these important effects, GPCR trafficking actively shapes the cellular signaling response by altering the location and timing of specific receptor-mediated signaling reactions. Here, we review key experimental evidence underlying this expanding view, focused on GPCR signaling mediated through activation of heterotrimeric G proteins located in the cytoplasm. We then discuss lingering and emerging questions regarding the interface between GPCR signaling and trafficking.
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Affiliation(s)
- Braden T Lobingier
- Department of Psychiatry and Department of Cellular and Molecular Pharmacology, University of California, San Francisco School of Medicine, San Francisco, California
| | - Mark von Zastrow
- Department of Psychiatry and Department of Cellular and Molecular Pharmacology, University of California, San Francisco School of Medicine, San Francisco, California
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8
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Gendron L, Nagi K, Zeghal M, Giguère PM, Pineyro G. Molecular aspects of delta opioid receptors. OPIOID HORMONES 2019; 111:49-90. [DOI: 10.1016/bs.vh.2019.06.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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9
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Stoeber M, Jullié D, Lobingier BT, Laeremans T, Steyaert J, Schiller PW, Manglik A, von Zastrow M. A Genetically Encoded Biosensor Reveals Location Bias of Opioid Drug Action. Neuron 2018; 98:963-976.e5. [PMID: 29754753 DOI: 10.1016/j.neuron.2018.04.021] [Citation(s) in RCA: 188] [Impact Index Per Article: 31.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Revised: 03/26/2018] [Accepted: 04/17/2018] [Indexed: 11/16/2022]
Abstract
Opioid receptors (ORs) precisely modulate behavior when activated by native peptide ligands but distort behaviors to produce pathology when activated by non-peptide drugs. A fundamental question is how drugs differ from peptides in their actions on target neurons. Here, we show that drugs differ in the subcellular location at which they activate ORs. We develop a genetically encoded biosensor that directly detects ligand-induced activation of ORs and uncover a real-time map of the spatiotemporal organization of OR activation in living neurons. Peptide agonists produce a characteristic activation pattern initiated in the plasma membrane and propagating to endosomes after receptor internalization. Drugs produce a different activation pattern by additionally driving OR activation in the somatic Golgi apparatus and Golgi elements extending throughout the dendritic arbor. These results establish an approach to probe the cellular basis of neuromodulation and reveal that drugs distort the spatiotemporal landscape of neuronal OR activation.
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Affiliation(s)
- Miriam Stoeber
- Department of Psychiatry, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Damien Jullié
- Department of Psychiatry, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Braden T Lobingier
- Department of Psychiatry, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Toon Laeremans
- Structural Biology Brussels, Vrije Universiteit Brussel, 1050 Brussels, Belgium
| | - Jan Steyaert
- Structural Biology Brussels, Vrije Universiteit Brussel, 1050 Brussels, Belgium; VIB-VUB Center for Structural Biology, 1050 Brussels, Belgium
| | - Peter W Schiller
- Clinical Research Institute of Montreal, Montreal, QC H2W 1R7, Canada
| | - Aashish Manglik
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA 94143, USA; Department of Anesthesia, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Mark von Zastrow
- Department of Psychiatry, University of California, San Francisco, San Francisco, CA 94143, USA; Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94143, USA.
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10
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Gendron L, Cahill CM, von Zastrow M, Schiller PW, Pineyro G. Molecular Pharmacology of δ-Opioid Receptors. Pharmacol Rev 2017; 68:631-700. [PMID: 27343248 DOI: 10.1124/pr.114.008979] [Citation(s) in RCA: 86] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Opioids are among the most effective analgesics available and are the first choice in the treatment of acute severe pain. However, partial efficacy, a tendency to produce tolerance, and a host of ill-tolerated side effects make clinically available opioids less effective in the management of chronic pain syndromes. Given that most therapeutic opioids produce their actions via µ-opioid receptors (MOPrs), other targets are constantly being explored, among which δ-opioid receptors (DOPrs) are being increasingly considered as promising alternatives. This review addresses DOPrs from the perspective of cellular and molecular determinants of their pharmacological diversity. Thus, DOPr ligands are examined in terms of structural and functional variety, DOPrs' capacity to engage a multiplicity of canonical and noncanonical G protein-dependent responses is surveyed, and evidence supporting ligand-specific signaling and regulation is analyzed. Pharmacological DOPr subtypes are examined in light of the ability of DOPr to organize into multimeric arrays and to adopt multiple active conformations as well as differences in ligand kinetics. Current knowledge on DOPr targeting to the membrane is examined as a means of understanding how these receptors are especially active in chronic pain management. Insight into cellular and molecular mechanisms of pharmacological diversity should guide the rational design of more effective, longer-lasting, and better-tolerated opioid analgesics for chronic pain management.
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Affiliation(s)
- Louis Gendron
- Département de Pharmacologie-Physiologie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Centre de Recherche du CHU de Sherbrooke, Centre d'excellence en neurosciences de l'Univeristé de Sherbrooke, and Institut de Pharmacologie de Sherbrooke, Sherbrooke, Quebec, Canada (L.G.); Québec Pain Research Network, Sherbrooke, Quebec, Canada (L.G.); Departments of Anesthesiology and Perioperative Care and Pharmacology, University of California, Irvine, California (C.M.C.); Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada (C.M.C.); Departments of Psychiatry and Cellular and Molecular Pharmacology, University of California, San Francisco, California (M.v.Z.); Laboratory of Chemical Biology and Peptide Research, Clinical Research Institute of Montréal, Montreal, Quebec, Canada (P.W.S.); and Departments of Psychiatry, Pharmacology, and Neurosciences, Faculty of Medicine, University of Montréal and Sainte-Justine Hospital Research Center, Montreal, Quebec, Canada (G.P.)
| | - Catherine M Cahill
- Département de Pharmacologie-Physiologie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Centre de Recherche du CHU de Sherbrooke, Centre d'excellence en neurosciences de l'Univeristé de Sherbrooke, and Institut de Pharmacologie de Sherbrooke, Sherbrooke, Quebec, Canada (L.G.); Québec Pain Research Network, Sherbrooke, Quebec, Canada (L.G.); Departments of Anesthesiology and Perioperative Care and Pharmacology, University of California, Irvine, California (C.M.C.); Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada (C.M.C.); Departments of Psychiatry and Cellular and Molecular Pharmacology, University of California, San Francisco, California (M.v.Z.); Laboratory of Chemical Biology and Peptide Research, Clinical Research Institute of Montréal, Montreal, Quebec, Canada (P.W.S.); and Departments of Psychiatry, Pharmacology, and Neurosciences, Faculty of Medicine, University of Montréal and Sainte-Justine Hospital Research Center, Montreal, Quebec, Canada (G.P.)
| | - Mark von Zastrow
- Département de Pharmacologie-Physiologie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Centre de Recherche du CHU de Sherbrooke, Centre d'excellence en neurosciences de l'Univeristé de Sherbrooke, and Institut de Pharmacologie de Sherbrooke, Sherbrooke, Quebec, Canada (L.G.); Québec Pain Research Network, Sherbrooke, Quebec, Canada (L.G.); Departments of Anesthesiology and Perioperative Care and Pharmacology, University of California, Irvine, California (C.M.C.); Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada (C.M.C.); Departments of Psychiatry and Cellular and Molecular Pharmacology, University of California, San Francisco, California (M.v.Z.); Laboratory of Chemical Biology and Peptide Research, Clinical Research Institute of Montréal, Montreal, Quebec, Canada (P.W.S.); and Departments of Psychiatry, Pharmacology, and Neurosciences, Faculty of Medicine, University of Montréal and Sainte-Justine Hospital Research Center, Montreal, Quebec, Canada (G.P.)
| | - Peter W Schiller
- Département de Pharmacologie-Physiologie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Centre de Recherche du CHU de Sherbrooke, Centre d'excellence en neurosciences de l'Univeristé de Sherbrooke, and Institut de Pharmacologie de Sherbrooke, Sherbrooke, Quebec, Canada (L.G.); Québec Pain Research Network, Sherbrooke, Quebec, Canada (L.G.); Departments of Anesthesiology and Perioperative Care and Pharmacology, University of California, Irvine, California (C.M.C.); Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada (C.M.C.); Departments of Psychiatry and Cellular and Molecular Pharmacology, University of California, San Francisco, California (M.v.Z.); Laboratory of Chemical Biology and Peptide Research, Clinical Research Institute of Montréal, Montreal, Quebec, Canada (P.W.S.); and Departments of Psychiatry, Pharmacology, and Neurosciences, Faculty of Medicine, University of Montréal and Sainte-Justine Hospital Research Center, Montreal, Quebec, Canada (G.P.)
| | - Graciela Pineyro
- Département de Pharmacologie-Physiologie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Centre de Recherche du CHU de Sherbrooke, Centre d'excellence en neurosciences de l'Univeristé de Sherbrooke, and Institut de Pharmacologie de Sherbrooke, Sherbrooke, Quebec, Canada (L.G.); Québec Pain Research Network, Sherbrooke, Quebec, Canada (L.G.); Departments of Anesthesiology and Perioperative Care and Pharmacology, University of California, Irvine, California (C.M.C.); Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada (C.M.C.); Departments of Psychiatry and Cellular and Molecular Pharmacology, University of California, San Francisco, California (M.v.Z.); Laboratory of Chemical Biology and Peptide Research, Clinical Research Institute of Montréal, Montreal, Quebec, Canada (P.W.S.); and Departments of Psychiatry, Pharmacology, and Neurosciences, Faculty of Medicine, University of Montréal and Sainte-Justine Hospital Research Center, Montreal, Quebec, Canada (G.P.)
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11
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A PTEN-Regulated Checkpoint Controls Surface Delivery of δ Opioid Receptors. J Neurosci 2017; 37:3741-3752. [PMID: 28264976 DOI: 10.1523/jneurosci.2923-16.2017] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Revised: 01/26/2017] [Accepted: 02/14/2017] [Indexed: 12/13/2022] Open
Abstract
The δ opioid receptor (δR) is a promising alternate target for pain management because δR agonists show decreased abuse potential compared with current opioid analgesics that target the μ opioid receptor. A critical limitation in developing δR as an analgesic target, however, is that δR agonists show relatively low efficacy in vivo, requiring the use of high doses that often cause adverse effects, such as convulsions. Here we tested whether intracellular retention of δR in sensory neurons contributes to this low δR agonist efficacy in vivo by limiting surface δR expression. Using direct visualization of δR trafficking and localization, we define a phosphatase and tensin homolog (PTEN)-regulated checkpoint that retains δR in the Golgi and decreases surface delivery in rat and mice sensory neurons. PTEN inhibition releases δR from this checkpoint and stimulates delivery of exogenous and endogenous δR to the neuronal surface both in vitro and in vivo PTEN inhibition in vivo increases the percentage of TG neurons expressing δR on the surface and allows efficient δR-mediated antihyperalgesia in mice. Together, we define a critical role for PTEN in regulating the surface delivery and bioavailability of the δR, explain the low efficacy of δR agonists in vivo, and provide evidence that active δR relocation is a viable strategy to increase δR antinociception.SIGNIFICANCE STATEMENT Opioid analgesics, such as morphine, which target the μ opioid receptor (μR), have been the mainstay of pain management, but their use is highly limited by adverse effects and their variable efficacy in chronic pain. Identifying alternate analgesic targets is therefore of great significance. Although the δ opioid receptor (δR) is an attractive option, a critical limiting factor in developing δR as a target has been the low efficacy of δR agonists. Why δR agonists show low efficacy is still under debate. This study provides mechanistic and functional data that intracellular localization of δR in neurons is a key factor that contributes to low agonist efficacy, and presents a proof of mechanism that relocating δR improves efficacy.
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Collybolide is a novel biased agonist of κ-opioid receptors with potent antipruritic activity. Proc Natl Acad Sci U S A 2016; 113:6041-6. [PMID: 27162327 DOI: 10.1073/pnas.1521825113] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Among the opioid receptors, the κ-opioid receptor (κOR) has been gaining considerable attention as a potential therapeutic target for the treatment of complex CNS disorders including depression, visceral pain, and cocaine addiction. With an interest in discovering novel ligands targeting κOR, we searched natural products for unusual scaffolds and identified collybolide (Colly), a nonnitrogenous sesquiterpene from the mushroom Collybia maculata. This compound has a furyl-δ-lactone core similar to that of Salvinorin A (Sal A), another natural product from the plant Salvia divinorum Characterization of the molecular pharmacological properties reveals that Colly, like Sal A, is a highly potent and selective κOR agonist. However, the two compounds differ in certain signaling and behavioral properties. Colly exhibits 10- to 50-fold higher potency in activating the mitogen-activated protein kinase pathway compared with Sal A. Taken with the fact that the two compounds are equipotent for inhibiting adenylyl cyclase activity, these results suggest that Colly behaves as a biased agonist of κOR. Behavioral studies also support the biased agonistic activity of Colly in that it exhibits ∼10-fold higher potency in blocking non-histamine-mediated itch compared with Sal A, and this difference is not seen in pain attenuation by these two compounds. These results represent a rare example of functional selectivity by two natural products that act on the same receptor. The biased agonistic activity, along with an easily modifiable structure compared with Sal A, makes Colly an ideal candidate for the development of novel therapeutics targeting κOR with reduced side effects.
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Gomes I, Bobeck EN, Margolis EB, Gupta A, Sierra S, Fakira AK, Fujita W, Müller TD, Müller A, Tschöp MH, Kleinau G, Fricker LD, Devi LA. Identification of GPR83 as the receptor for the neuroendocrine peptide PEN. Sci Signal 2016; 9:ra43. [PMID: 27117253 DOI: 10.1126/scisignal.aad0694] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
PEN is an abundant peptide in the brain that has been implicated in the regulation of feeding. We identified a receptor for PEN in mouse hypothalamus and Neuro2A cells. PEN bound to and activated GPR83, a G protein (heterotrimeric guanine nucleotide)-binding protein)-coupled receptor (GPCR). Reduction of GPR83 expression in mouse brain and Neuro2A cells reduced PEN binding and signaling, consistent with GPR83 functioning as the major receptor for PEN. In some brain regions, GPR83 colocalized with GPR171, a GPCR that binds the neuropeptide bigLEN, another neuropeptide that is involved in feeding and is generated from the same precursor protein as is PEN. Coexpression of these two receptors in cell lines altered the signaling properties of each receptor, suggesting a functional interaction. Our data established PEN as a neuropeptide that binds GPR83 and suggested that these two ligand-receptor systems-PEN-GPR83 and bigLEN-GPR171-may be functionally coupled in the regulation of feeding.
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Affiliation(s)
- Ivone Gomes
- Department of Pharmacology and Systems Therapeutics, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Erin N Bobeck
- Department of Pharmacology and Systems Therapeutics, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Elyssa B Margolis
- Department of Neurology, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Achla Gupta
- Department of Pharmacology and Systems Therapeutics, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Salvador Sierra
- Department of Pharmacology and Systems Therapeutics, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Amanda K Fakira
- Department of Pharmacology and Systems Therapeutics, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Wakako Fujita
- Department of Pharmacology and Systems Therapeutics, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Timo D Müller
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), 85764 Neuherberg, Germany. Division of Metabolic Diseases, Department of Medicine, Technische Universität München, 80333 Munich, Germany
| | - Anne Müller
- Institut für Experimentelle Pädiatrische Endokrinologie, Charité-Universitätsmedizin, 13125 Berlin, Germany
| | - Matthias H Tschöp
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), 85764 Neuherberg, Germany. Division of Metabolic Diseases, Department of Medicine, Technische Universität München, 80333 Munich, Germany
| | - Gunnar Kleinau
- Institut für Experimentelle Pädiatrische Endokrinologie, Charité-Universitätsmedizin, 13125 Berlin, Germany
| | - Lloyd D Fricker
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Lakshmi A Devi
- Department of Pharmacology and Systems Therapeutics, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA. Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA.
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Reynolds AL, Alvarez Y, Sasore T, Waghorne N, Butler CT, Kilty C, Smith AJ, McVicar C, Wong VHY, Galvin O, Merrigan S, Osman J, Grebnev G, Sjölander A, Stitt AW, Kennedy BN. Phenotype-based Discovery of 2-[(E)-2-(Quinolin-2-yl)vinyl]phenol as a Novel Regulator of Ocular Angiogenesis. J Biol Chem 2016; 291:7242-55. [PMID: 26846851 DOI: 10.1074/jbc.m115.710665] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Indexed: 12/21/2022] Open
Abstract
Retinal angiogenesis is tightly regulated to meet oxygenation and nutritional requirements. In diseases such as proliferative diabetic retinopathy and neovascular age-related macular degeneration, uncontrolled angiogenesis can lead to blindness. Our goal is to better understand the molecular processes controlling retinal angiogenesis and discover novel drugs that inhibit retinal neovascularization. Phenotype-based chemical screens were performed using the ChemBridge Diverset(TM)library and inhibition of hyaloid vessel angiogenesis in Tg(fli1:EGFP) zebrafish. 2-[(E)-2-(Quinolin-2-yl)vinyl]phenol, (quininib) robustly inhibits developmental angiogenesis at 4-10 μmin zebrafish and significantly inhibits angiogenic tubule formation in HMEC-1 cells, angiogenic sprouting in aortic ring explants, and retinal revascularization in oxygen-induced retinopathy mice. Quininib is well tolerated in zebrafish, human cell lines, and murine eyes. Profiling screens of 153 angiogenic and inflammatory targets revealed that quininib does not directly target VEGF receptors but antagonizes cysteinyl leukotriene receptors 1 and 2 (CysLT1-2) at micromolar IC50values. In summary, quininib is a novel anti-angiogenic small-molecule CysLT receptor antagonist. Quininib inhibits angiogenesis in a range of cell and tissue systems, revealing novel physiological roles for CysLT signaling. Quininib has potential as a novel therapeutic agent to treat ocular neovascular pathologies and may complement current anti-VEGF biological agents.
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Affiliation(s)
- Alison L Reynolds
- From the University College Dublin School of Biomolecular and Biomedical Science, Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland
| | - Yolanda Alvarez
- From the University College Dublin School of Biomolecular and Biomedical Science, Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland
| | - Temitope Sasore
- From the University College Dublin School of Biomolecular and Biomedical Science, Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland
| | - Nora Waghorne
- From the University College Dublin School of Biomolecular and Biomedical Science, Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland
| | - Clare T Butler
- From the University College Dublin School of Biomolecular and Biomedical Science, Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland
| | - Claire Kilty
- From the University College Dublin School of Biomolecular and Biomedical Science, Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland
| | - Andrew J Smith
- From the University College Dublin School of Biomolecular and Biomedical Science, Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland
| | - Carmel McVicar
- the Centre for Experimental Medicine, Queen's University Belfast, Wellcome-Wolfson Building, 97 Lisburn Road, Belfast, BT9 7BL, United Kingdom, and
| | - Vickie H Y Wong
- the Centre for Experimental Medicine, Queen's University Belfast, Wellcome-Wolfson Building, 97 Lisburn Road, Belfast, BT9 7BL, United Kingdom, and
| | - Orla Galvin
- From the University College Dublin School of Biomolecular and Biomedical Science, Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland
| | - Stephanie Merrigan
- From the University College Dublin School of Biomolecular and Biomedical Science, Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland
| | - Janina Osman
- the Division of Cell and Experimental Pathology, Department of Translational Medicine, Lund University, Skåne University Hospital, 20502 Malmö, Sweden
| | - Gleb Grebnev
- From the University College Dublin School of Biomolecular and Biomedical Science, Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland
| | - Anita Sjölander
- the Division of Cell and Experimental Pathology, Department of Translational Medicine, Lund University, Skåne University Hospital, 20502 Malmö, Sweden
| | - Alan W Stitt
- the Centre for Experimental Medicine, Queen's University Belfast, Wellcome-Wolfson Building, 97 Lisburn Road, Belfast, BT9 7BL, United Kingdom, and
| | - Breandán N Kennedy
- From the University College Dublin School of Biomolecular and Biomedical Science, Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland,
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Abstract
This paper is the thirty-seventh consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2014 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 (endogenous opioids and receptors), and the roles of these opioid peptides and receptors in pain and analgesia (pain and analgesia); stress and social status (human studies); tolerance and dependence (opioid mediation of other analgesic responses); learning and memory (stress and social status); eating and drinking (stress-induced analgesia); alcohol and drugs of abuse (emotional responses in opioid-mediated behaviors); sexual activity and hormones, pregnancy, development and endocrinology (opioid involvement in stress response regulation); mental illness and mood (tolerance and dependence); seizures and neurologic disorders (learning and memory); electrical-related activity and neurophysiology (opiates and conditioned place preferences (CPP)); general activity and locomotion (eating and drinking); gastrointestinal, renal and hepatic functions (alcohol and drugs of abuse); cardiovascular responses (opiates and ethanol); respiration and thermoregulation (opiates and THC); and immunological responses (opiates and stimulants). This paper is the thirty-seventh consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2014 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 (endogenous opioids and receptors), and the roles of these opioid peptides and receptors in pain and analgesia (pain and analgesia); stress and social status (human studies); tolerance and dependence (opioid mediation of other analgesic responses); learning and memory (stress and social status); eating and drinking (stress-induced analgesia); alcohol and drugs of abuse (emotional responses in opioid-mediated behaviors); sexual activity and hormones, pregnancy, development and endocrinology (opioid involvement in stress response regulation); mental illness and mood (tolerance and dependence); seizures and neurologic disorders (learning and memory); electrical-related activity and neurophysiology (opiates and conditioned place preferences (CPP)); general activity and locomotion (eating and drinking); gastrointestinal, renal and hepatic functions (alcohol and drugs of abuse); cardiovascular responses (opiates and ethanol); respiration and thermoregulation (opiates and THC); and immunological responses (opiates and stimulants).
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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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16
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Geppetti P, Veldhuis N, Lieu T, Bunnett N. G Protein-Coupled Receptors: Dynamic Machines for Signaling Pain and Itch. Neuron 2015; 88:635-49. [DOI: 10.1016/j.neuron.2015.11.001] [Citation(s) in RCA: 103] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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17
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Siuda ER, Copits BA, Schmidt MJ, Baird MA, Al-Hasani R, Planer WJ, Funderburk SC, McCall JG, Gereau RW, Bruchas MR. Spatiotemporal control of opioid signaling and behavior. Neuron 2015; 86:923-935. [PMID: 25937173 DOI: 10.1016/j.neuron.2015.03.066] [Citation(s) in RCA: 110] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2014] [Revised: 03/06/2015] [Accepted: 03/29/2015] [Indexed: 01/06/2023]
Abstract
Optogenetics is now a widely accepted tool for spatiotemporal manipulation of neuronal activity. However, a majority of optogenetic approaches use binary on/off control schemes. Here, we extend the optogenetic toolset by developing a neuromodulatory approach using a rationale-based design to generate a Gi-coupled, optically sensitive, mu-opioid-like receptor, which we term opto-MOR. We demonstrate that opto-MOR engages canonical mu-opioid signaling through inhibition of adenylyl cyclase, activation of MAPK and G protein-gated inward rectifying potassium (GIRK) channels and internalizes with kinetics similar to that of the mu-opioid receptor. To assess in vivo utility, we expressed a Cre-dependent viral opto-MOR in RMTg/VTA GABAergic neurons, which led to a real-time place preference. In contrast, expression of opto-MOR in GABAergic neurons of the ventral pallidum hedonic cold spot led to real-time place aversion. This tool has generalizable application for spatiotemporal control of opioid signaling and, furthermore, can be used broadly for mimicking endogenous neuronal inhibition pathways.
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Affiliation(s)
- Edward R Siuda
- Department of Anesthesiology, Basic Research Division, Washington University in St. Louis, St. Louis, MO 63110, USA; Division of Biological and Biomedical Sciences, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Bryan A Copits
- Department of Anesthesiology, Basic Research Division, Washington University in St. Louis, St. Louis, MO 63110, USA; Washington University Pain Center, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Martin J Schmidt
- Department of Anesthesiology, Basic Research Division, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Madison A Baird
- Department of Anesthesiology, Basic Research Division, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Ream Al-Hasani
- Department of Anesthesiology, Basic Research Division, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - William J Planer
- Department of Anesthesiology, Basic Research Division, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Samuel C Funderburk
- Department of Anesthesiology, Basic Research Division, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Jordan G McCall
- Department of Anesthesiology, Basic Research Division, Washington University in St. Louis, St. Louis, MO 63110, USA; Division of Biological and Biomedical Sciences, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Robert W Gereau
- Department of Anesthesiology, Basic Research Division, Washington University in St. Louis, St. Louis, MO 63110, USA; Division of Biological and Biomedical Sciences, Washington University School of Medicine, St. Louis, MO 63110, USA; Washington University Pain Center, Washington University in St. Louis, St. Louis, MO 63110, USA; Department of Anatomy and Neurobiology, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Michael R Bruchas
- Department of Anesthesiology, Basic Research Division, Washington University in St. Louis, St. Louis, MO 63110, USA; Division of Biological and Biomedical Sciences, Washington University School of Medicine, St. Louis, MO 63110, USA; Washington University Pain Center, Washington University in St. Louis, St. Louis, MO 63110, USA; Department of Anatomy and Neurobiology, Washington University in St. Louis, St. Louis, MO 63110, USA; Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO 63110, USA.
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18
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Gupta A, Fujita W, Gomes I, Bobeck E, Devi LA. Endothelin-converting enzyme 2 differentially regulates opioid receptor activity. Br J Pharmacol 2014; 172:704-19. [PMID: 24990314 DOI: 10.1111/bph.12833] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Revised: 06/17/2014] [Accepted: 06/24/2014] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND AND PURPOSE Opioid receptor function is modulated by post-activation events such as receptor endocytosis, recycling and/or degradation. While it is generally understood that the peptide ligand gets co-endocytosed with the receptor, relatively few studies have investigated the role of the endocytosed peptide and peptide processing enzymes in regulating receptor function. In this study, we focused on endothelin-converting enzyme 2 (ECE2), a member of the neprilysin family of metallopeptidases that exhibits an acidic pH optimum, localizes to an intracellular compartment and selectively processes neuropeptides including opioid peptides in vitro, and examined its role in modulating μ receptor recycling and resensitization. EXPERIMENTAL APPROACH The effect of ECE2 inhibition on hydrolysis of the endocytosed peptide was examined using thin-layer chromatography and on μ opioid receptor trafficking using either elisa or microscopy. The effect of ECE2 inhibition on receptor signalling was measured using a cAMP assay and, in vivo, on antinociception induced by intrathecally administered opioids by the tail-flick assay. KEY RESULTS The highly selective ECE2 inhibitor, S136492, significantly impaired μ receptor recycling and signalling by only those ligands that are ECE2 substrates and this was seen both in heterologous cells and in cells endogenously co-expressing μ receptors with ECE2. We also found that ECE2 inhibition attenuated antinociception mediated only by opioid peptides that are ECE2 substrates. CONCLUSIONS AND IMPLICATIONS These results suggest that ECE2, by selectively processing endogenous opioid peptides in the endocytic compartment, plays a role in modulating opioid receptor activity. 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)
- A Gupta
- Department of Pharmacology and Systems Therapeutics, Icahn School of Medicine at Mount Sinai, New York, NY, USA
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