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Green HM, Manning JJ, Greig IR, Ross RA, Finlay DB, Glass M. Positive allosteric modulation of the cannabinoid CB 1 receptor potentiates endocannabinoid signalling and changes ERK1/2 phosphorylation kinetics. Br J Pharmacol 2024; 181:3642-3662. [PMID: 38831545 DOI: 10.1111/bph.16433] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Revised: 04/16/2024] [Accepted: 04/20/2024] [Indexed: 06/05/2024] Open
Abstract
BACKGROUND AND PURPOSE Activation of CB1 by exogenous agonists causes adverse effects in vivo. Positive allosteric modulation may offer improved therapeutic potential and a reduced on-target adverse effect profile compared with orthosteric agonists, due to reduced desensitisation/tolerance, but this has not been directly tested. This study investigated the ability of PAMs/ago-PAMs to induce receptor regulation pathways, including desensitisation and receptor internalisation. EXPERIMENTAL APPROACH Bioluminescence resonance energy transfer (BRET) assays in HEK293 cells were performed to investigate G protein dissociation, ERK1/2 phosphorylation and β-arrestin 2 translocation, while immunocytochemistry was performed to measure internalisation of CB1 in response to the PAMs ZCZ011, GAT229 and ABD1236 alone and in combination with the orthosteric agonists AEA, 2-AG, and AMB-FUBINACA. KEY RESULTS ZCZ011, GAT229 and ABD1236 were allosteric agonists in all pathways tested. The ago-PAM ZCZ011 induced a biphasic ERK1/2 phosphorylation time course compared to transient activation by orthosteric agonists. In combination with 2-AG but not AEA or AMB-FUBINACA, ZCZ011 and ABD1236 caused the transient peak of ERK1/2 phosphorylation to become sustained. All PAMs increased the potency and efficacy of AEA-induced signalling in all pathways tested; however, no notable potentiation of 2-AG or AMB-FUBINACA was observed. CONCLUSION AND IMPLICATIONS Ago-PAMs can potentiate endocannabinoid CB1 agonism by AEA to a larger extent compared with 2-AG. However, all compounds were found to be allosteric agonists and induce activation of CB1 in the absence of endocannabinoid, including β-arrestin 2 recruitment and internalisation. Thus, the spatiotemporal signalling of endogenous cannabinoids will not be retained in vivo.
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Affiliation(s)
- Hayley M Green
- Department of Pharmacology and Toxicology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Jamie J Manning
- Department of Pharmacology and Toxicology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Ian R Greig
- School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Aberdeen, UK
| | - Ruth A Ross
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, Canada
| | - David B Finlay
- Department of Pharmacology and Toxicology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Michelle Glass
- Department of Pharmacology and Toxicology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
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Green HM, Fellner DMJ, Finlay DB, Furkert DP, Glass M. Determination of the Cannabinoid CB1 Receptor's Positive Allosteric Modulator Binding Site through Mutagenesis Studies. Pharmaceuticals (Basel) 2024; 17:154. [PMID: 38399369 PMCID: PMC10892375 DOI: 10.3390/ph17020154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Revised: 01/18/2024] [Accepted: 01/21/2024] [Indexed: 02/25/2024] Open
Abstract
Positive allosteric modulators (PAMs) of the cannabinoid CB1 receptor (CB1) offer potential therapeutic advantages in the treatment of neuropathic pain and addiction by avoiding the adverse effects associated with orthosteric CB1 activation. Here, molecular modeling and mutagenesis were used to identify residues central to PAM activity at CB1. Six putative allosteric binding sites were identified in silico, including novel sites previously associated with cholesterol binding, and key residues within each site were mutated to alanine. The recently determined ZCZ011 binding site was found to be essential for allosteric agonism, as GAT228, GAT229 and ZCZ011 all increased wild-type G protein dissociation in the absence of an orthosteric ligand; activity that was abolished in mutants F191A3.27 and I169A2.56. PAM activity was demonstrated for ZCZ011 in the presence of the orthosteric ligand CP55940, which was only abolished in I169A2.56. In contrast, the PAM activity of GAT229 was reduced for mutants R220A3.56, L404A8.50, F191A3.27 and I169A2.56. This indicates that allosteric modulation may represent the net effect of binding at multiple sites, and that allosteric agonism is likely to be mediated via the ZCZ011 site. This study underlines the need for detailed understanding of ligand receptor interactions in the search for pure CB1 allosteric modulators.
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Affiliation(s)
- Hayley M. Green
- Department of Pharmacology and Toxicology, School of Biomedical Sciences, University of Otago, Dunedin 9016, New Zealand; (H.M.G.); (D.B.F.)
| | - Daniel M. J. Fellner
- School of Chemical Sciences, Faculty of Science, University of Auckland, Auckland 1142, New Zealand; (D.M.J.F.); (D.P.F.)
| | - David B. Finlay
- Department of Pharmacology and Toxicology, School of Biomedical Sciences, University of Otago, Dunedin 9016, New Zealand; (H.M.G.); (D.B.F.)
| | - Daniel P. Furkert
- School of Chemical Sciences, Faculty of Science, University of Auckland, Auckland 1142, New Zealand; (D.M.J.F.); (D.P.F.)
- Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland, Auckland 1142, New Zealand
| | - Michelle Glass
- Department of Pharmacology and Toxicology, School of Biomedical Sciences, University of Otago, Dunedin 9016, New Zealand; (H.M.G.); (D.B.F.)
- Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland, Auckland 1142, New Zealand
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Won W, Kim D, Shin E, Lee CJ. Mapping Astrocytic and Neuronal μ-opioid Receptor Expression in Various Brain Regions Using MOR-mCherry Reporter Mouse. Exp Neurobiol 2023; 32:395-409. [PMID: 38196135 PMCID: PMC10789176 DOI: 10.5607/en23039] [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: 12/09/2023] [Revised: 12/23/2023] [Accepted: 12/27/2023] [Indexed: 01/11/2024] Open
Abstract
The μ-opioid receptor (MOR) is a class of opioid receptors characterized by a high affinity for β-endorphin and morphine. MOR is a G protein-coupled receptor (GPCR) that plays a role in reward and analgesic effects. While expression of MOR has been well established in neurons and microglia, astrocytic MOR expression has been less clear. Recently, we have reported that MOR is expressed in hippocampal astrocytes, and its activation has a critical role in the establishment of conditioned place preference. Despite this critical role, the expression and function of astrocytic MOR from other brain regions are still unknown. Here, we report that MOR is significantly expressed in astrocytes and GABAergic neurons from various brain regions including the hippocampus, nucleus accumbens, periaqueductal gray, amygdala, and arcuate nucleus. Using the MOR-mCherry reporter mice and Imaris analysis, we demonstrate that astrocytic MOR expression exceeded 60% in all tested regions. Also, we observed similar MOR expression of GABAergic neurons as shown in the previous distribution studies and it is noteworthy that MOR expression is particularly in parvalbumin (PV)-positive neurons. Furthermore, consistent with the normal MOR function observed in the MOR-mCherry mouse, our study also demonstrates intact MOR functionality in astrocytes through iGluSnFr-mediated glutamate imaging. Finally, we show the sex-difference in the expression pattern of MOR in PV-positive neurons, but not in the GABAergic neurons and astrocytes. Taken together, our findings highlight a substantial astrocytic MOR presence across various brain regions.
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Affiliation(s)
- Woojin Won
- Center for Cognition and Sociality, Institute for Basic Science (IBS), Daejeon 34126, Korea
| | - Daeun Kim
- Center for Cognition and Sociality, Institute for Basic Science (IBS), Daejeon 34126, Korea
- Department of Biomedical Engineering, College of Information and Biotechnology, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Korea
| | - Eunjin Shin
- Center for Cognition and Sociality, Institute for Basic Science (IBS), Daejeon 34126, Korea
| | - C. Justin Lee
- Center for Cognition and Sociality, Institute for Basic Science (IBS), Daejeon 34126, Korea
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Abstract
This paper is the forty-fifth consecutive installment of the annual anthological review of research concerning the endogenous opioid system, summarizing articles published during 2022 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides and receptors as well as effects of opioid/opiate agonists and antagonists. The review is subdivided into the following specific topics: molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors (1), the roles of these opioid peptides and receptors in pain and analgesia in animals (2) and humans (3), opioid-sensitive and opioid-insensitive effects of nonopioid analgesics (4), opioid peptide and receptor involvement in tolerance and dependence (5), stress and social status (6), learning and memory (7), eating and drinking (8), drug abuse and alcohol (9), sexual activity and hormones, pregnancy, development and endocrinology (10), mental illness and mood (11), seizures and neurologic disorders (12), electrical-related activity and neurophysiology (13), general activity and locomotion (14), gastrointestinal, renal and hepatic functions (15), cardiovascular responses (16), respiration and thermoregulation (17), and immunological responses (18).
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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, USA.
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Zhang Y, Beachy PA. Cellular and molecular mechanisms of Hedgehog signalling. Nat Rev Mol Cell Biol 2023; 24:668-687. [PMID: 36932157 DOI: 10.1038/s41580-023-00591-1] [Citation(s) in RCA: 43] [Impact Index Per Article: 43.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/14/2023] [Indexed: 03/19/2023]
Abstract
The Hedgehog signalling pathway has crucial roles in embryonic tissue patterning, postembryonic tissue regeneration, and cancer, yet aspects of Hedgehog signal transmission and reception have until recently remained unclear. Biochemical and structural studies surprisingly reveal a central role for lipids in Hedgehog signalling. The signal - Hedgehog protein - is modified by cholesterol and palmitate during its biogenesis, thereby necessitating specialized proteins such as the transporter Dispatched and several lipid-binding carriers for cellular export and receptor engagement. Additional lipid transactions mediate response to the Hedgehog signal, including sterol activation of the transducer Smoothened. Access of sterols to Smoothened is regulated by the apparent sterol transporter and Hedgehog receptor Patched, whose activity is blocked by Hedgehog binding. Alongside these lipid-centric mechanisms and their relevance to pharmacological pathway modulation, we discuss emerging roles of Hedgehog pathway activity in stem cells or their cellular niches, with translational implications for regeneration and restoration of injured or diseased tissues.
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Affiliation(s)
- Yunxiao Zhang
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA, USA
- Howard Hughes Medical Institute and Neuroscience Department, The Scripps Research Institute, La Jolla, CA, USA
| | - Philip A Beachy
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA, USA.
- Department of Urology, Stanford University School of Medicine, Stanford, CA, USA.
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA, USA.
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Ray AP, Thakur N, Pour NG, Eddy MT. Dual mechanisms of cholesterol-GPCR interactions that depend on membrane phospholipid composition. Structure 2023; 31:836-847.e6. [PMID: 37236187 PMCID: PMC10330489 DOI: 10.1016/j.str.2023.05.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 02/25/2023] [Accepted: 05/01/2023] [Indexed: 05/28/2023]
Abstract
Cholesterol is a critical component of mammalian cell membranes and an allosteric modulator of G protein-coupled receptors (GPCRs), but divergent views exist on the mechanisms by which cholesterol influences receptor functions. Leveraging the benefits of lipid nanodiscs, i.e., quantitative control of lipid composition, we observe distinct impacts of cholesterol in the presence and absence of anionic phospholipids on the function-related conformational dynamics of the human A2A adenosine receptor (A2AAR). Direct receptor-cholesterol interactions drive activation of agonist-bound A2AAR in membranes containing zwitterionic phospholipids. Intriguingly, the presence of anionic lipids attenuates cholesterol's impact through direct interactions with the receptor, highlighting a more complex role for cholesterol that depends on membrane phospholipid composition. Targeted amino acid replacements at two frequently predicted cholesterol interaction sites showed distinct impacts of cholesterol at different receptor locations, demonstrating the ability to delineate different roles of cholesterol in modulating receptor signaling and maintaining receptor structural integrity.
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Affiliation(s)
- Arka Prabha Ray
- Department of Chemistry, University of Florida, 126 Sisler Hall, Gainesville, FL 32611, USA
| | - Naveen Thakur
- Department of Chemistry, University of Florida, 126 Sisler Hall, Gainesville, FL 32611, USA
| | - Niloofar Gopal Pour
- Department of Chemistry, University of Florida, 126 Sisler Hall, Gainesville, FL 32611, USA
| | - Matthew T Eddy
- Department of Chemistry, University of Florida, 126 Sisler Hall, Gainesville, FL 32611, USA.
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Chronis IB, Puthenveedu MA. Patching holes in the mechanism of opioid tolerance. Trends Pharmacol Sci 2023; 44:70-72. [PMID: 36435677 PMCID: PMC10320836 DOI: 10.1016/j.tips.2022.11.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2022] [Revised: 11/16/2022] [Accepted: 11/17/2022] [Indexed: 11/27/2022]
Abstract
Tolerance is a significant obstacle to use of opioids as safe pain relieving drugs, but the cellular processes that result in tolerance have remained elusive. A new study by Maza and colleagues identifies the protein Patched domain-containing 1 (PTCHD1) and its effects on cellular cholesterol as potential targets for preventing opioid tolerance.
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Affiliation(s)
- Ian B Chronis
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48109, USA.
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