1
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Manning JJ, Finlay DB, Glass M. GPCR kinase subtype requirements for arrestin-2 and -3 translocation to the cannabinoid CB 1 receptor and the consequences on G protein signalling. Biochem Pharmacol 2024; 224:116190. [PMID: 38604257 DOI: 10.1016/j.bcp.2024.116190] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Revised: 04/02/2024] [Accepted: 04/04/2024] [Indexed: 04/13/2024]
Abstract
Arrestins are key negative regulators of G Protein-Coupled Receptors (GPCRs) through mediation of G protein desensitisation and receptor internalisation. Arrestins can also contribute to signal transduction by scaffolding downstream signalling effectors for activation. GPCR kinase (GRK) enzymes phosphorylate the intracellular C-terminal domain, or intracellular loop regions of GPCRs to promote arrestin interaction. There are seven different GRK subtypes, which may uniquely phosphorylate the C-terminal tail in a type of 'phosphorylation barcode,' potentially differentially contributing to arrestin translocation and arrestin-dependent signalling. Such contributions may be exploited to develop arrestin-biased ligands. Here, we examine the effect of different GRK subtypes on the ability to promote translocation of arrestin-2 and arrestin-3 to the cannabinoid CB1 receptor (CB1) with a range of ligands. We find that most GRK subtypes (including visual GRK1) can enhance arrestin-2 and -3 translocation to CB1, and that GRK-dependent changes in arrestin-2 and arrestin-3 translocation were broadly shared for most agonists tested. GRK2/3 generally enhanced arrestin translocation more than the other GRK subtypes, with some small differences between ligands. We also explore the interplay between G protein activity and GRK2/3-dependent arrestin translocation, highlighting that high-efficacy G protein agonists will cause GRK2/3 dependent arrestin translocation. This study supports the hypothesis that arrestin-biased ligands for CB1 must engage GRK5/6 rather than GRK2/3, and G protein-biased ligands must have inherently low efficacy.
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Affiliation(s)
- Jamie J Manning
- Department of Pharmacology and Toxicology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - 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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2
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Leo LM, Al-Zoubi R, Hurst DP, Stephan AP, Zhao P, Tilley DG, Miess E, Schulz S, Abood ME, Reggio PH. The NPXXY Motif Regulates β-Arrestin Recruitment by the CB1 Cannabinoid Receptor. Cannabis Cannabinoid Res 2023; 8:731-748. [PMID: 35792570 PMCID: PMC10589503 DOI: 10.1089/can.2021.0223] [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] [Indexed: 11/12/2022] Open
Abstract
Background: Activation of signaling effectors by G-protein coupled receptors (GPCRs) depends on different molecular mechanisms triggered by conserved amino acid residues. Although studies have focused on the G-protein signaling state, the mechanism for β-arrestin signaling by CB1 is not yet well defined. Studies have indicated that transmembrane helix 7 (TMH7) and the highly conserved NPXXY motif can be subject to different conformational changes in response to biased ligands and could therefore participate in a molecular mechanism to trigger β-arrestin recruitment. Objective: To investigate the effect of mutations in the NPXXY motif on different signaling pathways activated by the CB1 receptor. Materials and Methods: Point mutations of the NPXXY motif and associated residues were generated in the CB1 receptor using site-directed mutagenesis and transfection into HEK-293 cells. Signaling by wild-type and mutant receptors was analyzed by quantifying inhibition of cAMP, and by β-arrestin recruitment assays. Results: We found that N7.49 and Y7.53 are essential for β-arrestin recruitment by CB1. N7.49A and Y7.53F impair β-arrestin signaling, with no effect on G-protein signaling. We found a regulatory role for residue I2.43; I2.43 interacts with Y7.53, affecting its positioning. Reducing steric bulk at I2.43 (I2.43A) enhances β-arrestin1 recruitment, while introducing a polar residue (I2.43T) reduces β-arrestin recruitment. Conclusions: These findings point to a novel mechanism for β-arrestin recruitment, implicating amino acids in the NPXXY motif as critical for the putative β-arrestin biased conformational state of Class A GPCRs.
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Affiliation(s)
- Luciana M. Leo
- Center for Substance Abuse Research, Lewis Katz School of Medicine at Temple University, Philadelphia, Pennsylvania, USA
| | - Rufaida Al-Zoubi
- Department of Medicinal Chemistry and Pharmacognosy, Faculty of Pharmacy, Jordan University of Science & Technology, Irbid, Jordan
| | - Dow P. Hurst
- Chemistry and Biochemistry Department, UNC Greensboro, Greensboro, North Carolina, USA
| | - Anna P. Stephan
- Center for Substance Abuse Research, Lewis Katz School of Medicine at Temple University, Philadelphia, Pennsylvania, USA
| | - Pingwei Zhao
- Center for Substance Abuse Research, Lewis Katz School of Medicine at Temple University, Philadelphia, Pennsylvania, USA
| | - Douglas G. Tilley
- Center for Translational Medicine, Lewis Katz School of Medicine at Temple University, Philadelphia, Pennsylvania, USA
| | - Elke Miess
- Department of Pharmacology and Toxicology, Jena University Hospital-Friedrich Schiller University Jena, Jena, Germany
| | - Stefan Schulz
- Department of Pharmacology and Toxicology, Jena University Hospital-Friedrich Schiller University Jena, Jena, Germany
| | - Mary E. Abood
- Center for Substance Abuse Research, Lewis Katz School of Medicine at Temple University, Philadelphia, Pennsylvania, USA
| | - Patricia H. Reggio
- Chemistry and Biochemistry Department, UNC Greensboro, Greensboro, North Carolina, USA
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3
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Leo LM, Abood ME. CB1 Cannabinoid Receptor Signaling and Biased Signaling. Molecules 2021; 26:molecules26175413. [PMID: 34500853 PMCID: PMC8433814 DOI: 10.3390/molecules26175413] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Revised: 08/30/2021] [Accepted: 09/03/2021] [Indexed: 12/11/2022] Open
Abstract
The CB1 cannabinoid receptor is a G-protein coupled receptor highly expressed throughout the central nervous system that is a promising target for the treatment of various disorders, including anxiety, pain, and neurodegeneration. Despite the wide therapeutic potential of CB1, the development of drug candidates is hindered by adverse effects, rapid tolerance development, and abuse potential. Ligands that produce biased signaling—the preferential activation of a signaling transducer in detriment of another—have been proposed as a strategy to dissociate therapeutic and adverse effects for a variety of G-protein coupled receptors. However, biased signaling at the CB1 receptor is poorly understood due to a lack of strongly biased agonists. Here, we review studies that have investigated the biased signaling profile of classical cannabinoid agonists and allosteric ligands, searching for a potential therapeutic advantage of CB1 biased signaling in different pathological states. Agonist and antagonist bound structures of CB1 and proposed mechanisms of action of biased allosteric modulators are used to discuss a putative molecular mechanism for CB1 receptor activation and biased signaling. Current studies suggest that allosteric binding sites on CB1 can be explored to yield biased ligands that favor or hinder conformational changes important for biased signaling.
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Lowe H, Toyang N, Steele B, Bryant J, Ngwa W. The Endocannabinoid System: A Potential Target for the Treatment of Various Diseases. Int J Mol Sci 2021; 22:9472. [PMID: 34502379 PMCID: PMC8430969 DOI: 10.3390/ijms22179472] [Citation(s) in RCA: 82] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Revised: 08/23/2021] [Accepted: 08/26/2021] [Indexed: 02/06/2023] Open
Abstract
The Endocannabinoid System (ECS) is primarily responsible for maintaining homeostasis, a balance in internal environment (temperature, mood, and immune system) and energy input and output in living, biological systems. In addition to regulating physiological processes, the ECS directly influences anxiety, feeding behaviour/appetite, emotional behaviour, depression, nervous functions, neurogenesis, neuroprotection, reward, cognition, learning, memory, pain sensation, fertility, pregnancy, and pre-and post-natal development. The ECS is also involved in several pathophysiological diseases such as cancer, cardiovascular diseases, and neurodegenerative diseases. In recent years, genetic and pharmacological manipulation of the ECS has gained significant interest in medicine, research, and drug discovery and development. The distribution of the components of the ECS system throughout the body, and the physiological/pathophysiological role of the ECS-signalling pathways in many diseases, all offer promising opportunities for the development of novel cannabinergic, cannabimimetic, and cannabinoid-based therapeutic drugs that genetically or pharmacologically modulate the ECS via inhibition of metabolic pathways and/or agonism or antagonism of the receptors of the ECS. This modulation results in the differential expression/activity of the components of the ECS that may be beneficial in the treatment of a number of diseases. This manuscript in-depth review will investigate the potential of the ECS in the treatment of various diseases, and to put forth the suggestion that many of these secondary metabolites of Cannabis sativa L. (hereafter referred to as "C. sativa L." or "medical cannabis"), may also have potential as lead compounds in the development of cannabinoid-based pharmaceuticals for a variety of diseases.
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Affiliation(s)
- Henry Lowe
- Biotech R & D Institute, University of the West Indies, Mona 99999, Jamaica; (H.L.); (J.B.)
- Vilotos Pharmaceuticals Inc., Baltimore, MD 21202, USA;
- Flavocure Biotech Inc., Baltimore, MD 21202, USA
- Department of Medicine, University of Maryland Medical School, Baltimore, MD 21202, USA
| | - Ngeh Toyang
- Vilotos Pharmaceuticals Inc., Baltimore, MD 21202, USA;
- Flavocure Biotech Inc., Baltimore, MD 21202, USA
| | - Blair Steele
- Biotech R & D Institute, University of the West Indies, Mona 99999, Jamaica; (H.L.); (J.B.)
| | - Joseph Bryant
- Biotech R & D Institute, University of the West Indies, Mona 99999, Jamaica; (H.L.); (J.B.)
| | - Wilfred Ngwa
- Brigham and Women’s Hospital, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02215, USA;
- Johns Hopkins University School of Medicine, Baltimore, MD 21218, USA
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5
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Garai S, Leo LM, Szczesniak AM, Hurst DP, Schaffer PC, Zagzoog A, Black T, Deschamps JR, Miess E, Schulz S, Janero DR, Straiker A, Pertwee RG, Abood ME, Kelly MEM, Reggio PH, Laprairie RB, Thakur GA. Discovery of a Biased Allosteric Modulator for Cannabinoid 1 Receptor: Preclinical Anti-Glaucoma Efficacy. J Med Chem 2021; 64:8104-8126. [PMID: 33826336 DOI: 10.1021/acs.jmedchem.1c00040] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
We apply the magic methyl effect to improve the potency/efficacy of GAT211, the prototypic 2-phenylindole-based cannabinoid type-1 receptor (CB1R) agonist-positive allosteric modulator (ago-PAM). Introducing a methyl group at the α-position of nitro group generated two diastereomers, the greater potency and efficacy of erythro, (±)-9 vs threo, (±)-10 constitutes the first demonstration of diastereoselective CB1R-allosteric modulator interaction. Of the (±)-9 enantiomers, (-)-(S,R)-13 evidenced improved potency over GAT211 as a CB1R ago-PAM, whereas (+)-(R,S)-14 was a CB1R allosteric agonist biased toward G protein- vs β-arrestin1/2-dependent signaling. (-)-(S,R)-13 and (+)-(R,S)-14 were devoid of undesirable side effects (triad test), and (+)-(R,S)-14 reduced intraocular pressure with an unprecedentedly long duration of action in a murine glaucoma model. (-)-(S,R)-13 docked into both a CB1R extracellular PAM and intracellular allosteric-agonist site(s), whereas (+)-(R,S)-14 preferentially engaged only the latter. Exploiting G-protein biased CB1R-allosteric modulation can offer safer therapeutic candidates for glaucoma and, potentially, other diseases.
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Affiliation(s)
- Sumanta Garai
- Department of Pharmaceutical Sciences, Bouvé College of Health Sciences, Northeastern University, Boston, Massachusetts 02115, United States
| | - Luciana M Leo
- Center for Substance Abuse Research, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania 19140, United States
| | - Anna-Maria Szczesniak
- Department of Pharmacology and Department of Ophthalmology and Visual Sciences, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada
| | - Dow P Hurst
- Center for Drug Discovery, University of North Carolina Greensboro, Greensboro, North Carolina 27402, United States
| | - Peter C Schaffer
- Department of Pharmaceutical Sciences, Bouvé College of Health Sciences, Northeastern University, Boston, Massachusetts 02115, United States
| | - Ayat Zagzoog
- College of Pharmacy and Nutrition, University of Saskatchewan, 104 Clinic Pl, Saskatoon, Saskatchewan S7N2Z4, Canada
| | - Tallan Black
- College of Pharmacy and Nutrition, University of Saskatchewan, 104 Clinic Pl, Saskatoon, Saskatchewan S7N2Z4, Canada
| | - Jeffrey R Deschamps
- Naval Research Laboratory, Code 6930, 4555 Overlook Avenue, Washington, District of Columbia 20375, United States
| | - Elke Miess
- Department of Pharmacology and Toxicology, Jena University Hospital-Friedrich Schiller University Jena, D-07747 Jena, Germany
| | - Stefan Schulz
- Department of Pharmacology and Toxicology, Jena University Hospital-Friedrich Schiller University Jena, D-07747 Jena, Germany
| | - David R Janero
- Department of Pharmaceutical Sciences, Bouvé College of Health Sciences, Northeastern University, Boston, Massachusetts 02115, United States
| | - Alex Straiker
- The Gill Center and the Department of Psychological & Brain Sciences, Indiana University, 1101 E. 10th St, Bloomington, Indiana 47405, United States
| | - Roger G Pertwee
- School of Medicine, Medical Sciences and Nutrition, Institute of Medical Sciences, University of Aberdeen, Aberdeen AB25 2ZD, Scotland, U.K
| | - Mary E Abood
- Center for Substance Abuse Research, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania 19140, United States
| | - Melanie E M Kelly
- Department of Pharmacology and Department of Ophthalmology and Visual Sciences, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada
| | - Patricia H Reggio
- Center for Drug Discovery, University of North Carolina Greensboro, Greensboro, North Carolina 27402, United States
| | - Robert B Laprairie
- College of Pharmacy and Nutrition, University of Saskatchewan, 104 Clinic Pl, Saskatoon, Saskatchewan S7N2Z4, Canada
- Department of Pharmacology and Department of Ophthalmology and Visual Sciences, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada
| | - Ganesh A Thakur
- Department of Pharmaceutical Sciences, Bouvé College of Health Sciences, Northeastern University, Boston, Massachusetts 02115, United States
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6
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Manning JJ, Green HM, Glass M, Finlay DB. Pharmacological selection of cannabinoid receptor effectors: Signalling, allosteric modulation and bias. Neuropharmacology 2021; 193:108611. [PMID: 34000272 DOI: 10.1016/j.neuropharm.2021.108611] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 04/26/2021] [Accepted: 05/10/2021] [Indexed: 12/14/2022]
Abstract
The type-1 cannabinoid receptor (CB1) is a promising drug target for a wide range of diseases. However, many existing and novel candidate ligands for CB1 have shown only limited therapeutic potential. Indeed, no ligands are currently approved for the clinic except formulations of the phytocannabinoids Δ9-THC and CBD and a small number of analogues. A key limitation of many promising CB1 ligands are their on-target adverse effects, notably including psychoactivity (agonists) and depression/suicidal ideation (inverse agonists). Recent drug development attempts have therefore focussed on altering CB1 signalling profiles in two ways. Firstly, with compounds that enhance or reduce the signalling of endogenous (endo-) cannabinoids, namely allosteric modulators. Secondly, with compounds that probe the capability of selectively targeting specific cellular signalling pathways that may mediate therapeutic effects using biased ligands. This review will summarise the current paradigm of CB1 signalling in terms of the intracellular transduction pathways acted on by the receptor. The development of compounds that selectively activate CB1 signalling pathways, whether allosterically or via orthosteric agonist bias, will also be addressed.
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Affiliation(s)
- Jamie J Manning
- Department of Pharmacology and Toxicology, University of Otago, Dunedin, New Zealand, PO Box 56, Dunedin, 9054, New Zealand
| | - Hayley M Green
- Department of Pharmacology and Toxicology, University of Otago, Dunedin, New Zealand, PO Box 56, Dunedin, 9054, New Zealand
| | - Michelle Glass
- Department of Pharmacology and Toxicology, University of Otago, Dunedin, New Zealand, PO Box 56, Dunedin, 9054, New Zealand
| | - David B Finlay
- Department of Pharmacology and Toxicology, University of Otago, Dunedin, New Zealand, PO Box 56, Dunedin, 9054, New Zealand.
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7
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Slosky LM, Caron MG, Barak LS. Biased Allosteric Modulators: New Frontiers in GPCR Drug Discovery. Trends Pharmacol Sci 2021; 42:283-299. [PMID: 33581873 PMCID: PMC9797227 DOI: 10.1016/j.tips.2020.12.005] [Citation(s) in RCA: 82] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 12/21/2020] [Accepted: 12/22/2020] [Indexed: 12/31/2022]
Abstract
G protein-coupled receptors (GPCRs) are the largest class of cell surface receptors in the genome and the most successful family of targets of FDA-approved drugs. New frontiers in GPCR drug discovery remain, however, as achieving receptor subtype selectivity and controlling off- and on-target side effects are not always possible with classic agonist and antagonist ligands. These challenges may be overcome by focusing development efforts on allosteric ligands that confer signaling bias. Biased allosteric modulators (BAMs) are an emerging class of GPCR ligands that engage less well-conserved regulatory motifs outside the orthosteric pocket and exert pathway-specific effects on receptor signaling. The unique ways that BAMs texturize receptor signaling present opportunities to fine-tune physiology and develop safer, more selective therapeutics. Here, we provide a conceptual framework for understanding the pharmacology of BAMs, explore their therapeutic potential, and discuss strategies for their discovery.
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Affiliation(s)
- Lauren M. Slosky
- Department of Cell Biology, Duke University, Durham, NC 27710, USA
| | - Marc G. Caron
- Departments of Cell Biology, Neurobiology and Medicine, Duke University, Durham, NC 27710, USA,Correspondence: (L.S.B.); (M.G.C.)
| | - Lawrence S. Barak
- Department of Cell Biology, Duke University, Durham, NC 27710, USA,Correspondence: (L.S.B.); (M.G.C.)
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8
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Mielnik CA, Lam VM, Ross RA. CB 1 allosteric modulators and their therapeutic potential in CNS disorders. Prog Neuropsychopharmacol Biol Psychiatry 2021; 106:110163. [PMID: 33152384 DOI: 10.1016/j.pnpbp.2020.110163] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 09/30/2020] [Accepted: 10/29/2020] [Indexed: 01/05/2023]
Abstract
CB1 is the most abundant GPCR found in the mammalian brain. It has garnered considerable attention as a potential therapeutic drug target. CB1 is involved in a wide range of physiological and psychiatric processes and has the potential to be targeted in a wide range of disease states. However, most of the selective and non-selective synthetic CB1 agonists and antagonists/inverse agonists developed to date are primarily used as research tools. No novel synthetic cannabinoids are currently in the clinic for use in psychiatric illness; synthetic analogues of the phytocannabinoid THC are on the market to treat nausea and vomiting caused by cancer chemotherapy, along with off-label use for pain. Novel strategies are being explored to target CB1, but with emphasis on the elimination or mitigation of the potential psychiatric adverse effects that are observed by central agonism/antagonism of CB1. New pharmacological options are being pursued that may avoid these adverse effects while preserving the potential therapeutic benefits of CB1 modulation. Allosteric modulation of CB1 is one such approach. In this review, we will summarize and critically analyze both the in vitro characterization and in vivo validation of CB1 allosteric modulators developed to date, with a focus on CNS therapeutic effects.
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Affiliation(s)
- Catharine A Mielnik
- Department of Pharmacology & Toxicology, University of Toronto, ON M5S 1A8, Canada
| | - Vincent M Lam
- Department of Pharmacology & Toxicology, University of Toronto, ON M5S 1A8, Canada
| | - Ruth A Ross
- Department of Pharmacology & Toxicology, University of Toronto, ON M5S 1A8, Canada.
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9
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Fasciani I, Petragnano F, Aloisi G, Marampon F, Carli M, Scarselli M, Maggio R, Rossi M. Allosteric Modulators of G Protein-Coupled Dopamine and Serotonin Receptors: A New Class of Atypical Antipsychotics. Pharmaceuticals (Basel) 2020; 13:ph13110388. [PMID: 33202534 PMCID: PMC7696972 DOI: 10.3390/ph13110388] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Revised: 11/06/2020] [Accepted: 11/11/2020] [Indexed: 12/23/2022] Open
Abstract
Schizophrenia was first described by Emil Krapelin in the 19th century as one of the major mental illnesses causing disability worldwide. Since the introduction of chlorpromazine in 1952, strategies aimed at modifying the activity of dopamine receptors have played a major role for the treatment of schizophrenia. The introduction of atypical antipsychotics with clozapine broadened the range of potential targets for the treatment of this psychiatric disease, as they also modify the activity of the serotoninergic receptors. Interestingly, all marketed drugs for schizophrenia bind to the orthosteric binding pocket of the receptor as competitive antagonists or partial agonists. In recent years, a strong effort to develop allosteric modulators as potential therapeutic agents for schizophrenia was made, mainly for the several advantages in their use. In particular, the allosteric binding sites are topographically distinct from the orthosteric pockets, and thus drugs targeting these sites have a higher degree of receptor subunit specificity. Moreover, “pure” allosteric modulators maintain the temporal and spatial fidelity of native orthosteric ligand. Furthermore, allosteric modulators have a “ceiling effect”, and their modulatory effect is saturated above certain concentrations. In this review, we summarize the progresses made in the identification of allosteric drugs for dopamine and serotonin receptors, which could lead to a new generation of atypical antipsychotics with a better profile, especially in terms of reduced side effects.
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Affiliation(s)
- Irene Fasciani
- Department of Biotechnological and Applied Clinical Sciences, University of l’Aquila, 67100 L’Aquila, Italy; (I.F.); (F.P.); (G.A.)
| | - Francesco Petragnano
- Department of Biotechnological and Applied Clinical Sciences, University of l’Aquila, 67100 L’Aquila, Italy; (I.F.); (F.P.); (G.A.)
| | - Gabriella Aloisi
- Department of Biotechnological and Applied Clinical Sciences, University of l’Aquila, 67100 L’Aquila, Italy; (I.F.); (F.P.); (G.A.)
| | - Francesco Marampon
- Department of Radiotherapy, “Sapienza” University of Rome, Policlinico Umberto I, 00161 Rome, Italy;
| | - Marco Carli
- Department of Translational Research and New Technology in Medicine and Surgery, University of Pisa, 56126 Pisa, Italy; (M.C.); (M.S.)
| | - Marco Scarselli
- Department of Translational Research and New Technology in Medicine and Surgery, University of Pisa, 56126 Pisa, Italy; (M.C.); (M.S.)
| | - Roberto Maggio
- Department of Biotechnological and Applied Clinical Sciences, University of l’Aquila, 67100 L’Aquila, Italy; (I.F.); (F.P.); (G.A.)
- Correspondence:
| | - Mario Rossi
- Institute of Molecular Cell and Systems Biology, University of Glasgow, Glasgow G12 8QQ, UK;
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10
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Structure of an allosteric modulator bound to the CB1 cannabinoid receptor. Nat Chem Biol 2019; 15:1199-1205. [PMID: 31659318 DOI: 10.1038/s41589-019-0387-2] [Citation(s) in RCA: 108] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2019] [Accepted: 09/09/2019] [Indexed: 02/05/2023]
Abstract
The CB1 receptor mediates the central nervous system response to cannabinoids, and is a drug target for pain, anxiety and seizures. CB1 also responds to allosteric modulators, which influence cannabinoid binding and efficacy. To understand the mechanism of these compounds, we solved the crystal structure of CB1 with the negative allosteric modulator (NAM) ORG27569 and the agonist CP55940. The structure reveals that the NAM binds to an extrahelical site within the inner leaflet of the membrane, which overlaps with a conserved site of cholesterol interaction in many G protein-coupled receptors (GPCRs). The ternary structure with ORG27569 and CP55940 captures an intermediate state of the receptor, in which aromatic residues at the base of the agonist-binding pocket adopt an inactive conformation despite the large contraction of the orthosteric pocket. The structure illustrates a potential strategy for drug modulation of CB1 and other class A GPCRs.
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11
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Al-Zoubi R, Morales P, Reggio PH. Structural Insights into CB1 Receptor Biased Signaling. Int J Mol Sci 2019; 20:E1837. [PMID: 31013934 PMCID: PMC6515405 DOI: 10.3390/ijms20081837] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Revised: 04/09/2019] [Accepted: 04/11/2019] [Indexed: 12/21/2022] Open
Abstract
The endocannabinoid system has emerged as a promising target for the treatment of numerous diseases, including cancer, neurodegenerative disorders, and metabolic syndromes. Thus far, two cannabinoid receptors, CB1 and CB2, have been discovered, which are found predominantly in the central nervous system (CB1) or the immune system (CB2), among other organs and tissues. CB1 receptor ligands have been shown to induce a complex pattern of intracellular effects. The binding of a ligand induces distinct conformational changes in the receptor, which will eventually translate into distinct intracellular signaling pathways through coupling to specific intracellular effector proteins. These proteins can mediate receptor desensitization, trafficking, or signaling. Ligand specificity and selectivity, complex cellular components, and the concomitant expression of other proteins (which either regulate the CB1 receptor or are regulated by the CB1 receptor) will affect the therapeutic outcome of its targeting. With an increased interest in G protein-coupled receptors (GPCR) research, in-depth studies using mutations, biological assays, and spectroscopic techniques (such as NMR, EPR, MS, FRET, and X-ray crystallography), as well as computational modelling, have begun to reveal a set of concerted structural features in Class A GPCRs which relate to signaling pathways and the mechanisms of ligand-induced activation, deactivation, or activity modulation. This review will focus on the structural features of the CB1 receptor, mutations known to bias its signaling, and reported studies of CB1 receptor ligands to control its specific signaling.
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Affiliation(s)
- Rufaida Al-Zoubi
- Department of Medicinal Chemistry and Pharmacognosy, Faculty of Pharmacy, Jordan University of Science & Technology, P.O.BOX 3030, Irbid 22110, Jordan.
| | - Paula Morales
- Departamento de Química-Física Biológica, Instituto de Química Física Rocasolano (IQFR-CSIC), Serrano 119, 28006 Madrid, Spain.
| | - Patricia H Reggio
- Chemistry and Biochemistry Department, UNC Greensboro, Greensboro, NC 27412, USA.
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12
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Lu D, Immadi SS, Wu Z, Kendall DA. Translational potential of allosteric modulators targeting the cannabinoid CB 1 receptor. Acta Pharmacol Sin 2019; 40:324-335. [PMID: 30333554 DOI: 10.1038/s41401-018-0164-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Accepted: 08/27/2018] [Indexed: 12/11/2022] Open
Abstract
The cannabinoid type-1 (CB1) receptor, a G-protein-coupled receptor, is an attractive target for drug discovery due to its involvement in many physiological processes. Historically, drug discovery efforts targeting the CB1 receptor have focused on the development of orthosteric ligands that interact with the active site to which endogenous cannabinoids bind. Research performed over the last several decades has revealed substantial difficulties in translating CB1 orthosteric ligands into druggable candidates. The difficulty is mainly due to the adverse effects associated with orthosteric CB1 ligands. Recent discoveries of allosteric CB1 modulators provide tremendous opportunities to develop CB1 ligands with novel mechanisms of action; these ligands may potentially improve the pharmacological effects and enhance drug safety in treating the disorders by regulating the functions of the CB1 receptor. In this paper, we review and summarize the complex pharmacological profiles of each class of CB1 allosteric modulators, the development of new classes of CB1 allosteric modulators and the results from in vivo assessments of their therapeutic value.
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Khurana L, Mackie K, Piomelli D, Kendall DA. Modulation of CB1 cannabinoid receptor by allosteric ligands: Pharmacology and therapeutic opportunities. Neuropharmacology 2017; 124:3-12. [PMID: 28527758 PMCID: PMC5540789 DOI: 10.1016/j.neuropharm.2017.05.018] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Revised: 04/12/2017] [Accepted: 05/16/2017] [Indexed: 02/03/2023]
Abstract
Cannabinoid pharmacology has been intensely studied because of cannabis' pervasive medicinal and non-medicinal uses as well as for the therapeutic potential of cannabinoid-based drugs for the treatment of pain, anxiety, substance abuse, obesity, cancer and neurodegenerative disorders. The identification of allosteric modulators of the cannabinoid receptor 1 (CB1) has given a new direction to the development of cannabinoid-based therapeutics due to the many advantages offered by targeting allosteric site(s). Allosteric receptor modulators hold potential to develop subtype-specific and pathway-specific therapeutics. Here we briefly discuss the first-generation of allosteric modulators of CB1 receptor, their structure-activity relationships, signaling pathways and the allosteric binding site(s) on the CB1 receptor. This article is part of the Special Issue entitled "A New Dawn in Cannabinoid Neurobiology".
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Affiliation(s)
- Leepakshi Khurana
- Department of Pharmaceutical Sciences, University of Connecticut, Storrs, CT 06269, United States
| | - Ken Mackie
- Gill Center and Departmental of Psychological and Brain Sciences, Indiana University, Bloomington, IN 47405, United States
| | - Daniele Piomelli
- Department of Anatomy and Neurobiology, University of California, Irvine, CA 92697, United States; Department of Biological Chemistry, University of California, Irvine, CA 92697, United States
| | - Debra A Kendall
- Department of Pharmaceutical Sciences, University of Connecticut, Storrs, CT 06269, United States.
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Gamage TF, Farquhar CE, Lefever TW, Thomas BF, Nguyen T, Zhang Y, Wiley JL. The great divide: Separation between in vitro and in vivo effects of PSNCBAM-based CB 1 receptor allosteric modulators. Neuropharmacology 2017; 125:365-375. [PMID: 28803965 DOI: 10.1016/j.neuropharm.2017.08.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Revised: 07/25/2017] [Accepted: 08/09/2017] [Indexed: 01/08/2023]
Abstract
While allosteric modulators of the cannabinoid type-1 receptor (CB1) continue to be developed and characterized, the gap between the in vitro and in vivo data is widening, raising questions regarding translatability of their effects and biological relevance. Among the CB1 allosteric modulators, PSNCBAM-1 has received little attention regarding its effects in vivo. Recently, pregnenolone was reported to act as an allosteric modulator of CB1, blocking THC's effects in vitro and in vivo, highlighting the potential of CB1 allosteric modulators for treatment of cannabis intoxication. We investigated the pharmacological effects of PSNCBAM-1 and two structural analogs, RTICBM-15 and -28, as well as pregnenolone, in both signaling and behavioral assays including [35S]GTPγS binding, the cannabinoid tetrad and drug discrimination. While the CB1 allosteric modulator PSNCBAM-1 attenuated THC-induced anti-nociception and its structural analog RTICBM-28 reduced THC's potency in drug discrimination, most cannabinoid effects in mice were unaffected. In contrast to the mouse studies, PSNCBAM-1 and analogs insurmountably antagonized CP55,940- and THC-stimulated [35S]GTPγS binding and exhibited negative binding cooperativity with [3H]SR141716 with similar apparent affinities. Notably, RTICBM-28, which contains a cyano substitution at the 4-chlorophenyl position of PSNCBAM-1, exhibited enhanced binding cooperativity with CP55,940. In contrast to previous findings, pregnenolone did not block THC's effects in drug discrimination or [35S]GTPγS. These data further highlight the difficulty in translating pharmacological effects of CB1 allosteric modulators in vivo but confirm the established pharmacology of PSNCBAM-1 and analogs in molecular assays of CB1 receptor function.
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Affiliation(s)
- Thomas F Gamage
- RTI International, 3040 Cornwallis Road, Research Triangle Park, NC 27709-2194, USA.
| | - Charlotte E Farquhar
- RTI International, 3040 Cornwallis Road, Research Triangle Park, NC 27709-2194, USA
| | - Timothy W Lefever
- RTI International, 3040 Cornwallis Road, Research Triangle Park, NC 27709-2194, USA
| | - Brian F Thomas
- RTI International, 3040 Cornwallis Road, Research Triangle Park, NC 27709-2194, USA
| | - Thuy Nguyen
- RTI International, 3040 Cornwallis Road, Research Triangle Park, NC 27709-2194, USA
| | - Yanan Zhang
- RTI International, 3040 Cornwallis Road, Research Triangle Park, NC 27709-2194, USA
| | - Jenny L Wiley
- RTI International, 3040 Cornwallis Road, Research Triangle Park, NC 27709-2194, USA
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Abstract
The cannabinoid CB1 receptor is abundant in the central nervous system and regulates neuronal transmission and other key physiological processes including those leading to pain, inflammation, memory, and feeding behavior. CB1 is activated by the endogenous ligands, arachidonoyl ethanolamine and 2-arachidonoyl glycerol, by various synthetic ligands (e.g., CP55940), and by Δ9-tetrahydrocannabinol, the psychoactive component of Cannabis sativa. These CB1 ligands are orthosteric and transduce downstream signals by binding CB1 and primarily inducing Gi coupling, but Gs and β-arrestin coupling are also possible. Recently, allosteric modulators for CB1 were discovered that bind to topographically distinct sites and can noncompetitively impact the potency and efficacy of orthosteric compounds. These offer the exciting potential for mechanistic analyses and for developing therapeutics. Yet, it is critical to elucidate whether a compound is a positive allosteric modulator or a negative allosteric modulator of orthosteric ligand-induced CB1 profiles to understand pathway specificity and ameliorate diseases. In this chapter, we present equilibrium and kinetic binding analysis to reveal the impact of allosteric modulators on CB1. Also described are activities consistent with CB1 activation (or inactivation) and include cellular internalization of CB1 and downstream signaling patterns. Since many CB1 allosteric modulators do not enhance G protein coupling, it is critical to distinguish CB1 activation and biased signaling patterns via β-arrestin from CB1 inactivation. These strategies can illuminate pathway specificity and are valuable for the fine-tuning of CB1 function.
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Abstract
An agonist that acts through a single receptor can activate numerous signaling pathways. Recent studies have suggested that different ligands can differentially activate these pathways by stabilizing a limited range of receptor conformations, which in turn preferentially drive different downstream signaling cascades. This concept, termed "biased signaling" represents an exciting therapeutic opportunity to target specific pathways that elicit only desired effects, while avoiding undesired effects mediated by different signaling cascades. The cannabinoid receptors CB1 and CB2 each activate multiple pathways, and evidence is emerging for bias within these pathways. This review will summarize the current evidence for biased signaling through cannabinoid receptor subtypes CB1 and CB2.
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Affiliation(s)
- Mikkel Søes Ibsen
- Department of Pharmacology, School of Medical Sciences, University of Auckland, Auckland, New Zealand
| | - Mark Connor
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, 2 Technology Place, Macquarie University, New South Wales, Australia
| | - Michelle Glass
- Department of Pharmacology, School of Medical Sciences, University of Auckland, Auckland, New Zealand
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Priestley R, Glass M, Kendall D. Functional Selectivity at Cannabinoid Receptors. CANNABINOID PHARMACOLOGY 2017; 80:207-221. [DOI: 10.1016/bs.apha.2017.03.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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