1
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Kaoullas MG, Thal DM, Christopoulos A, Valant C. Ligand bias at the muscarinic acetylcholine receptor family: Opportunities and challenges. Neuropharmacology 2024; 258:110092. [PMID: 39067666 DOI: 10.1016/j.neuropharm.2024.110092] [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: 03/18/2024] [Revised: 06/25/2024] [Accepted: 07/24/2024] [Indexed: 07/30/2024]
Abstract
Muscarinic acetylcholine receptors (mAChRs) are G protein-coupled receptors (GPCRs) that are activated by the endogenous neurotransmitter, acetylcholine (ACh). Disruption of mAChR signalling has been associated with a variety of neurological disorders and non-neurological diseases. Consequently, the development of agonists and antagonists of the mAChRs has been a major avenue in drug discovery. Unfortunately, mAChR ligands are often associated with on-target side effects for two reasons. The first reason is due to the high sequence conservation at the orthosteric ACh binding site among all five receptor subtypes (M1-M5), making on-target subtype selectivity a major challenge. The second reason is due to on-target side effects of mAChR drugs that are associated with the pleiotropic nature of mAChR signalling at the level of a single mAChR subtype. Indeed, there is growing evidence that within the myriad of signalling events produced by mAChR ligands, some will have therapeutic benefits, whilst others may promote cholinergic side effects. This paradigm of drug action, known as ligand bias or biased agonism, is an attractive feature for next-generation mAChR drugs, as it holds the promise of developing drugs devoid of on-target adverse effects. Although relatively simple to detect and even quantify in vitro, ligand bias, as observed in recombinant systems, does not always translate to in vivo systems, which remains a major hurdle in GPCR drug discovery, including the mAChR family. Here we report recent studies that have attempted to detect and quantify ligand bias at the mAChR family, and briefly discuss the challenges associated with biased agonist drug development.
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Affiliation(s)
- Michaela G Kaoullas
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, 399 Royal Parade, 3052, VIC, Parkville, Melbourne, Australia
| | - David M Thal
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, 399 Royal Parade, 3052, VIC, Parkville, Melbourne, Australia
| | - Arthur Christopoulos
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, 399 Royal Parade, 3052, VIC, Parkville, Melbourne, Australia.
| | - Celine Valant
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, 399 Royal Parade, 3052, VIC, Parkville, Melbourne, Australia.
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2
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Saito A, Alvi S, Valant C, Christopoulos A, Carbone SE, Poole DP. Therapeutic potential of allosteric modulators for the treatment of gastrointestinal motility disorders. Br J Pharmacol 2024; 181:2232-2246. [PMID: 36565295 DOI: 10.1111/bph.16023] [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: 09/21/2022] [Revised: 11/24/2022] [Accepted: 12/09/2022] [Indexed: 12/25/2022] Open
Abstract
Gastrointestinal motility is tightly regulated by the enteric nervous system (ENS). Disruption of coordinated enteric nervous system activity can result in dysmotility. Pharmacological treatment options for dysmotility include targeting of G protein-coupled receptors (GPCRs) expressed by neurons of the enteric nervous system. Current GPCR-targeting drugs for motility disorders bind to the highly conserved endogenous ligand-binding site and promote indiscriminate activation or inhibition of the target receptor throughout the body. This can be associated with significant side-effect liability and a loss of physiological tone. Allosteric modulators of GPCRs bind to a distinct site from the endogenous ligand, which is typically less conserved across multiple receptor subtypes and can modulate endogenous ligand signalling. Allosteric modulation of GPCRs that are important for enteric nervous system function may provide effective relief from motility disorders while limiting side-effects. This review will focus on how allosteric modulators of GPCRs may influence gastrointestinal motility, using 5-hydroxytryptamine (5-HT), acetylcholine (ACh) and opioid receptors as examples. LINKED ARTICLES: This article is part of a themed issue Therapeutic Targeting of G Protein-Coupled Receptors: hot topics from the Australasian Society of Clinical and Experimental Pharmacologists and Toxicologists 2021 Virtual Annual Scientific Meeting. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v181.14/issuetoc.
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Affiliation(s)
- Ayame Saito
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Parkville, Victoria, Australia
| | - Sadia Alvi
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Parkville, Victoria, Australia
| | - Celine Valant
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Parkville, Victoria, Australia
| | - Arthur Christopoulos
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Parkville, Victoria, Australia
| | - Simona E Carbone
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Parkville, Victoria, Australia
| | - Daniel P Poole
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Parkville, Victoria, Australia
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3
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Skiba MA, Sterling SM, Rawson S, Zhang S, Xu H, Jiang H, Nemeth GR, Gilman MSA, Hurley JD, Shen P, Staus DP, Kim J, McMahon C, Lehtinen MK, Rockman HA, Barth P, Wingler LM, Kruse AC. Antibodies expand the scope of angiotensin receptor pharmacology. Nat Chem Biol 2024:10.1038/s41589-024-01620-6. [PMID: 38744986 DOI: 10.1038/s41589-024-01620-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Accepted: 04/12/2024] [Indexed: 05/16/2024]
Abstract
G-protein-coupled receptors (GPCRs) are key regulators of human physiology and are the targets of many small-molecule research compounds and therapeutic drugs. While most of these ligands bind to their target GPCR with high affinity, selectivity is often limited at the receptor, tissue and cellular levels. Antibodies have the potential to address these limitations but their properties as GPCR ligands remain poorly characterized. Here, using protein engineering, pharmacological assays and structural studies, we develop maternally selective heavy-chain-only antibody ('nanobody') antagonists against the angiotensin II type I receptor and uncover the unusual molecular basis of their receptor antagonism. We further show that our nanobodies can simultaneously bind to angiotensin II type I receptor with specific small-molecule antagonists and demonstrate that ligand selectivity can be readily tuned. Our work illustrates that antibody fragments can exhibit rich and evolvable pharmacology, attesting to their potential as next-generation GPCR modulators.
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Affiliation(s)
- Meredith A Skiba
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Sarah M Sterling
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
- Cryo-EM Facility at MIT.nano, Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Shaun Rawson
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Shuhao Zhang
- Interfaculty Institute of Bioengineering, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Huixin Xu
- Department of Pathology, Boston Children's Hospital, Boston, MA, USA
| | - Haoran Jiang
- Department of Medicine, Duke University Medical Center, Durham, NC, USA
| | - Genevieve R Nemeth
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Morgan S A Gilman
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Joseph D Hurley
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Pengxiang Shen
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
| | - Dean P Staus
- Department of Medicine, Duke University Medical Center, Durham, NC, USA
- Howard Hughes Medical Institute, Duke University Medical Center, Durham, NC, USA
- Septerna, South San Francisco, CA, USA
| | - Jihee Kim
- Department of Medicine, Duke University Medical Center, Durham, NC, USA
- Howard Hughes Medical Institute, Duke University Medical Center, Durham, NC, USA
| | - Conor McMahon
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
- Sanofi, Large Molecule Research, Cambridge, MA, USA
| | - Maria K Lehtinen
- Department of Pathology, Boston Children's Hospital, Boston, MA, USA
| | - Howard A Rockman
- Department of Medicine, Duke University Medical Center, Durham, NC, USA
- Department of Cell Biology, Duke University Medical Center, Durham, NC, USA
| | - Patrick Barth
- Interfaculty Institute of Bioengineering, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
- Ludwig Institute for Cancer Research Lausanne, Epalinges, Switzerland
| | - Laura M Wingler
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, NC, USA
| | - Andrew C Kruse
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA.
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4
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Do HN, Wang J, Miao Y. Deep Learning Dynamic Allostery of G-Protein-Coupled Receptors. JACS AU 2023; 3:3165-3180. [PMID: 38034960 PMCID: PMC10685416 DOI: 10.1021/jacsau.3c00503] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/26/2023] [Revised: 10/10/2023] [Accepted: 10/18/2023] [Indexed: 12/02/2023]
Abstract
G-protein-coupled receptors (GPCRs) make up the largest superfamily of human membrane proteins and represent primary targets of ∼1/3 of currently marketed drugs. Allosteric modulators have emerged as more selective drug candidates compared with orthosteric agonists and antagonists. However, many X-ray and cryo-EM structures of GPCRs resolved so far exhibit negligible differences upon the binding of positive and negative allosteric modulators (PAMs and NAMs). The mechanism of dynamic allosteric modulation in GPCRs remains unclear. In this work, we have systematically mapped dynamic changes in free energy landscapes of GPCRs upon binding of allosteric modulators using the Gaussian accelerated molecular dynamics (GaMD), deep learning (DL), and free energy prOfiling Workflow (GLOW). GaMD simulations were performed for a total of 66 μs on 44 GPCR systems in the presence and absence of the modulator. DL and free energy calculations revealed significantly reduced dynamic fluctuations and conformational space of GPCRs upon modulator binding. While the modulator-free GPCRs often sampled multiple low-energy conformational states, the NAMs and PAMs confined the inactive and active agonist-G-protein-bound GPCRs, respectively, to mostly only one specific conformation for signaling. Such cooperative effects were significantly reduced for binding of the selective modulators to "non-cognate" receptor subtypes. Therefore, GPCR allostery exhibits a dynamic "conformational selection" mechanism. In the absence of available modulator-bound structures as for most current GPCRs, it is critical to use a structural ensemble of representative GPCR conformations rather than a single structure for compound docking ("ensemble docking"), which will potentially improve structure-based design of novel allosteric drugs of GPCRs.
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Affiliation(s)
| | - Jinan Wang
- Computational Biology Program
and Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas 66047, United States
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5
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Eiger DS, Hicks C, Gardner J, Pham U, Rajagopal S. Location bias: A "Hidden Variable" in GPCR pharmacology. Bioessays 2023; 45:e2300123. [PMID: 37625014 DOI: 10.1002/bies.202300123] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Revised: 08/09/2023] [Accepted: 08/16/2023] [Indexed: 08/27/2023]
Abstract
G protein-coupled receptors (GPCRs) are the largest family of transmembrane receptors and primarily signal through two main effector proteins: G proteins and β-arrestins. Many agonists of GPCRs promote "biased" responses, in which different cellular signaling pathways are activated with varying efficacies. The mechanisms underlying biased signaling have not been fully elucidated, with many potential "hidden variables" that regulate this behavior. One contributor is "location bias," which refers to the generation of unique signaling cascades from a given GPCR depending upon the cellular location at which the receptor is signaling. Here, we review evidence that GPCRs are expressed at and traffic to various subcellular locations and discuss how location bias can impact the pharmacologic properties and characterization of GPCR agonists. We also evaluate how differences in subcellular environments can modulate GPCR signaling, highlight the physiological significance of subcellular GPCR signaling, and discuss the therapeutic potential of exploiting GPCR location bias.
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Affiliation(s)
- Dylan Scott Eiger
- Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts, USA
- Harvard Medical School, Boston, Massachusetts, USA
| | - Chloe Hicks
- Trinity College, Duke University, Durham, North Carolina, USA
| | - Julia Gardner
- Trinity College, Duke University, Durham, North Carolina, USA
| | - Uyen Pham
- Department of Biochemistry, Duke University, Durham, North Carolina, USA
| | - Sudarshan Rajagopal
- Department of Biochemistry, Duke University, Durham, North Carolina, USA
- Department of Medicine, Duke University, Durham, North Carolina, USA
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6
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Cheng L, Sun S, Wang H, Zhao C, Tian X, Liu Y, Fu P, Shao Z, Chai R, Yan W. Orthosteric ligand selectivity and allosteric probe dependence at Hydroxycarboxylic acid receptor HCAR2. Signal Transduct Target Ther 2023; 8:364. [PMID: 37743365 PMCID: PMC10518311 DOI: 10.1038/s41392-023-01625-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 07/24/2023] [Accepted: 08/21/2023] [Indexed: 09/26/2023] Open
Abstract
Hydroxycarboxylic acid receptor 2 (HCAR2), a member of Class A G-protein-coupled receptor (GPCR) family, plays a pivotal role in anti-lipolytic and anti-inflammatory effects, establishing it as a significant therapeutic target for treating dyslipidemia and inflammatory diseases. However, the mechanism underlying the signaling of HCAR2 induced by various types of ligands remains elusive. In this study, we elucidate the cryo-electron microscopy (cryo-EM) structure of Gi-coupled HCAR2 in complex with a selective agonist, MK-6892, resolved to a resolution of 2.60 Å. Our structural analysis reveals that MK-6892 occupies not only the orthosteric binding pocket (OBP) but also an extended binding pocket (EBP) within HCAR2. Pharmacological assays conducted in this study demonstrate that the OBP is a critical determinant for ligand selectivity among the HCARs subfamily. Moreover, we investigate the pharmacological properties of the allosteric modulator compound 9n, revealing its probe-dependent behavior on HCAR2 in response to varying orthosteric agonists. Collectively, our findings provide invaluable structural insights that contribute to a deeper understanding of the regulatory mechanisms governing HCAR2 signaling transduction mediated by both orthosteric and allosteric ligands.
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Affiliation(s)
- Lin Cheng
- Department of Otolaryngology Head and Neck Surgery, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, 610000, China
| | - Suyue Sun
- Division of Nephrology and Kidney Research Institute, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, 610041, China
| | - Heli Wang
- Division of Nephrology and Kidney Research Institute, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, 610041, China
| | - Chang Zhao
- Division of Nephrology and Kidney Research Institute, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, 610041, China
| | - Xiaowen Tian
- Division of Nephrology and Kidney Research Institute, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, 610041, China
| | - Ying Liu
- Division of Nephrology and Kidney Research Institute, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, 610041, China
| | - Ping Fu
- Division of Nephrology and Kidney Research Institute, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, 610041, China
| | - Zhenhua Shao
- Division of Nephrology and Kidney Research Institute, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, 610041, China.
- Frontiers Medical Center, Tianfu Jincheng Laboratory, Chengdu, 610212, China.
| | - Renjie Chai
- Department of Otolaryngology Head and Neck Surgery, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, 610000, China.
- State Key Laboratory of Digital Medical Engineering, Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, School of Life Sciences and Technology, Advanced Institute for Life and Health, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing, 210096, China.
- Co-Innovation Center of Neuroregeneration, Nantong University, Nantong, 226001, China.
| | - Wei Yan
- Division of Nephrology and Kidney Research Institute, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, 610041, China.
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7
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Burger WAC, Pham V, Vuckovic Z, Powers AS, Mobbs JI, Laloudakis Y, Glukhova A, Wootten D, Tobin AB, Sexton PM, Paul SM, Felder CC, Danev R, Dror RO, Christopoulos A, Valant C, Thal DM. Xanomeline displays concomitant orthosteric and allosteric binding modes at the M 4 mAChR. Nat Commun 2023; 14:5440. [PMID: 37673901 PMCID: PMC10482975 DOI: 10.1038/s41467-023-41199-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Accepted: 08/26/2023] [Indexed: 09/08/2023] Open
Abstract
The M4 muscarinic acetylcholine receptor (M4 mAChR) has emerged as a drug target of high therapeutic interest due to its expression in regions of the brain involved in the regulation of psychosis, cognition, and addiction. The mAChR agonist, xanomeline, has provided significant improvement in the Positive and Negative Symptom Scale (PANSS) scores in a Phase II clinical trial for the treatment of patients suffering from schizophrenia. Here we report the active state cryo-EM structure of xanomeline bound to the human M4 mAChR in complex with the heterotrimeric Gi1 transducer protein. Unexpectedly, two molecules of xanomeline were found to concomitantly bind to the monomeric M4 mAChR, with one molecule bound in the orthosteric (acetylcholine-binding) site and a second molecule in an extracellular vestibular allosteric site. Molecular dynamic simulations supports the structural findings, and pharmacological validation confirmed that xanomeline acts as a dual orthosteric and allosteric ligand at the human M4 mAChR. These findings provide a basis for further understanding xanomeline's complex pharmacology and highlight the myriad of ways through which clinically relevant ligands can bind to and regulate GPCRs.
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Affiliation(s)
- Wessel A C Burger
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia
- Australian Research Council Centre for Cryo-Electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia
| | - Vi Pham
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia
| | - Ziva Vuckovic
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia
| | - Alexander S Powers
- Department of Chemistry, Stanford University, Stanford, CA, 94305, USA
- Departments of Computer Science, Structural Biology, and Molecular and Cellular Physiology, Stanford University, Stanford, CA, 94305, USA
| | - Jesse I Mobbs
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia
- Australian Research Council Centre for Cryo-Electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia
| | - Yianni Laloudakis
- Department of Chemistry, Stanford University, Stanford, CA, 94305, USA
| | - Alisa Glukhova
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia
- Australian Research Council Centre for Cryo-Electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia
| | - Denise Wootten
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia
- Australian Research Council Centre for Cryo-Electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia
| | - Andrew B Tobin
- The Advanced Research Centre (ARC), Centre for Translational Science, School of Biomolecular Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Patrick M Sexton
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia
- Australian Research Council Centre for Cryo-Electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia
| | | | | | - Radostin Danev
- Graduate School of Medicine, University of Tokyo, N415, 7-3-1 Hongo, Bunkyo-ku, 113-0033, Tokyo, Japan
| | - Ron O Dror
- Departments of Computer Science, Structural Biology, and Molecular and Cellular Physiology, Stanford University, Stanford, CA, 94305, USA.
| | - Arthur Christopoulos
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia.
- Australian Research Council Centre for Cryo-Electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia.
- Neuromedicines Discovery Centre, Monash University, Parkville, VIC, 3052, Australia.
| | - Celine Valant
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia.
| | - David M Thal
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia.
- Australian Research Council Centre for Cryo-Electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia.
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8
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Pham V, Habben Jansen MCC, Thompson G, Heitman LH, Christopoulos A, Thal DM, Valant C. Role of Conserved Tyrosine Lid Residues in the Activation of the M 2 Muscarinic Acetylcholine Receptor. Mol Pharmacol 2023; 104:92-104. [PMID: 37348914 DOI: 10.1124/molpharm.122.000661] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 05/10/2023] [Accepted: 06/06/2023] [Indexed: 06/24/2023] Open
Abstract
The development of subtype selective small molecule drugs for the muscarinic acetylcholine receptor (mAChR) family has been challenging. The design of more selective ligands can be improved by understanding the structure and function of key amino acid residues that line ligand binding sites. Here we study the role of three conserved key tyrosine residues [Y1043.33, Y4036.51, and Y4267.39 (Ballesteros and Weinstein numbers in superscript)] at the human M2 mAChR, located at the interface between the orthosteric and allosteric binding sites of the receptor. We specifically focused on the role of the three tyrosine hydroxyl groups in the transition between the inactive and active conformations of the receptor by making phenylalanine point mutants. Single-point mutation at either of the three positions was sufficient to reduce the affinity of agonists by ∼100-fold for the M2 mAChR, whereas the affinity of antagonists remained largely unaffected. In contrast, neither of the mutations affected the efficacy of orthosteric agonists. When mutations were combined into double and triple M2 mAChR mutants, the affinity of antagonists was reduced by more than 100-fold compared with the wild-type M2 receptor. In contrast, the affinity of allosteric modulators, either negative or positive, was retained at all single and multiple mutations, but the degree of allosteric effect exerted on the endogenous ligand acetylcholine was affected at all mutants containing Y4267.39F. These findings will provide insights to consider when designing future mAChR ligands. SIGNIFICANCE STATEMENT: Structural studies demonstrated that three tyrosine residues between the orthosteric and allosteric sites of the M2 muscarinic acetylcholine receptor (mAChR) had different hydrogen bonding networks in the inactive and active conformations. The role of hydroxyl groups of the tyrosine residues on orthosteric and allosteric ligand pharmacology was unknown. We found that hydroxyl groups of the tyrosine residues differentially affected the molecular pharmacology of orthosteric and allosteric ligands. These results provide insights to consider when designing future mAChR ligands.
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Affiliation(s)
- Vi Pham
- Drug Discovery Biology (V.P., G.T., A.C., D.M.T., C.V.), ARC Industrial Transformation Training Centre for Cryo-Electron Microscopy of Membrane Proteins (A.C., D.M.T.), Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia; Drug Discovery and Safety, Universiteit Leiden, Leiden, The Netherlands (M.C.C.H.J., L.H.H.); and Neuromedicines Discovery Center, Monash University, Parkville, Victoria, Australia (A.C.)
| | - Maria Clazina Cornelia Habben Jansen
- Drug Discovery Biology (V.P., G.T., A.C., D.M.T., C.V.), ARC Industrial Transformation Training Centre for Cryo-Electron Microscopy of Membrane Proteins (A.C., D.M.T.), Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia; Drug Discovery and Safety, Universiteit Leiden, Leiden, The Netherlands (M.C.C.H.J., L.H.H.); and Neuromedicines Discovery Center, Monash University, Parkville, Victoria, Australia (A.C.)
| | - Geoff Thompson
- Drug Discovery Biology (V.P., G.T., A.C., D.M.T., C.V.), ARC Industrial Transformation Training Centre for Cryo-Electron Microscopy of Membrane Proteins (A.C., D.M.T.), Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia; Drug Discovery and Safety, Universiteit Leiden, Leiden, The Netherlands (M.C.C.H.J., L.H.H.); and Neuromedicines Discovery Center, Monash University, Parkville, Victoria, Australia (A.C.)
| | - Laura H Heitman
- Drug Discovery Biology (V.P., G.T., A.C., D.M.T., C.V.), ARC Industrial Transformation Training Centre for Cryo-Electron Microscopy of Membrane Proteins (A.C., D.M.T.), Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia; Drug Discovery and Safety, Universiteit Leiden, Leiden, The Netherlands (M.C.C.H.J., L.H.H.); and Neuromedicines Discovery Center, Monash University, Parkville, Victoria, Australia (A.C.)
| | - Arthur Christopoulos
- Drug Discovery Biology (V.P., G.T., A.C., D.M.T., C.V.), ARC Industrial Transformation Training Centre for Cryo-Electron Microscopy of Membrane Proteins (A.C., D.M.T.), Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia; Drug Discovery and Safety, Universiteit Leiden, Leiden, The Netherlands (M.C.C.H.J., L.H.H.); and Neuromedicines Discovery Center, Monash University, Parkville, Victoria, Australia (A.C.)
| | - David M Thal
- Drug Discovery Biology (V.P., G.T., A.C., D.M.T., C.V.), ARC Industrial Transformation Training Centre for Cryo-Electron Microscopy of Membrane Proteins (A.C., D.M.T.), Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia; Drug Discovery and Safety, Universiteit Leiden, Leiden, The Netherlands (M.C.C.H.J., L.H.H.); and Neuromedicines Discovery Center, Monash University, Parkville, Victoria, Australia (A.C.)
| | - Celine Valant
- Drug Discovery Biology (V.P., G.T., A.C., D.M.T., C.V.), ARC Industrial Transformation Training Centre for Cryo-Electron Microscopy of Membrane Proteins (A.C., D.M.T.), Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia; Drug Discovery and Safety, Universiteit Leiden, Leiden, The Netherlands (M.C.C.H.J., L.H.H.); and Neuromedicines Discovery Center, Monash University, Parkville, Victoria, Australia (A.C.)
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9
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Skiba MA, Sterling SM, Rawson S, Gilman MS, Xu H, Nemeth GR, Hurley JD, Shen P, Staus DP, Kim J, McMahon C, Lehtinen MK, Wingler LM, Kruse AC. Antibodies Expand the Scope of Angiotensin Receptor Pharmacology. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.23.554128. [PMID: 37662341 PMCID: PMC10473732 DOI: 10.1101/2023.08.23.554128] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/05/2023]
Abstract
G protein-coupled receptors (GPCRs) are key regulators of human physiology and are the targets of many small molecule research compounds and therapeutic drugs. While most of these ligands bind to their target GPCR with high affinity, selectivity is often limited at the receptor, tissue, and cellular level. Antibodies have the potential to address these limitations but their properties as GPCR ligands remain poorly characterized. Here, using protein engineering, pharmacological assays, and structural studies, we develop maternally selective heavy chain-only antibody ("nanobody") antagonists against the angiotensin II type I receptor (AT1R) and uncover the unusual molecular basis of their receptor antagonism. We further show that our nanobodies can simultaneously bind to AT1R with specific small-molecule antagonists and demonstrate that ligand selectivity can be readily tuned. Our work illustrates that antibody fragments can exhibit rich and evolvable pharmacology, attesting to their potential as next-generation GPCR modulators.
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Affiliation(s)
- Meredith A. Skiba
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Sarah M. Sterling
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Shaun Rawson
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Morgan S.A. Gilman
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Huixin Xu
- Department of Pathology, Boston Children’s Hospital, Boston, MA, 02115, USA
| | - Genevieve R. Nemeth
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Joseph D. Hurley
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Pengxiang Shen
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, 02138, USA
| | - Dean P. Staus
- Department of Medicine and Howard Hughes Medical Institute, Duke University Medical Center, Durham, NC 27710, USA
| | - Jihee Kim
- Department of Medicine and Howard Hughes Medical Institute, Duke University Medical Center, Durham, NC 27710, USA
| | - Conor McMahon
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Maria K. Lehtinen
- Department of Pathology, Boston Children’s Hospital, Boston, MA, 02115, USA
| | - Laura M. Wingler
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, NC 27710, USA
| | - Andrew C. Kruse
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
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10
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Vuckovic Z, Wang J, Pham V, Mobbs JI, Belousoff MJ, Bhattarai A, Burger WAC, Thompson G, Yeasmin M, Nawaratne V, Leach K, van der Westhuizen ET, Khajehali E, Liang YL, Glukhova A, Wootten D, Lindsley CW, Tobin A, Sexton P, Danev R, Valant C, Miao Y, Christopoulos A, Thal DM. Pharmacological hallmarks of allostery at the M4 muscarinic receptor elucidated through structure and dynamics. eLife 2023; 12:83477. [PMID: 37248726 DOI: 10.7554/elife.83477] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Accepted: 04/12/2023] [Indexed: 05/31/2023] Open
Abstract
Allosteric modulation of G protein-coupled receptors (GPCRs) is a major paradigm in drug discovery. Despite decades of research, a molecular-level understanding of the general principles that govern the myriad pharmacological effects exerted by GPCR allosteric modulators remains limited. The M4 muscarinic acetylcholine receptor (M4 mAChR) is a validated and clinically relevant allosteric drug target for several major psychiatric and cognitive disorders. In this study, we rigorously quantified the affinity, efficacy, and magnitude of modulation of two different positive allosteric modulators, LY2033298 (LY298) and VU0467154 (VU154), combined with the endogenous agonist acetylcholine (ACh) or the high-affinity agonist iperoxo (Ipx), at the human M4 mAChR. By determining the cryo-electron microscopy structures of the M4 mAChR, bound to a cognate Gi1 protein and in complex with ACh, Ipx, LY298-Ipx, and VU154-Ipx, and applying molecular dynamics simulations, we determine key molecular mechanisms underlying allosteric pharmacology. In addition to delineating the contribution of spatially distinct binding sites on observed pharmacology, our findings also revealed a vital role for orthosteric and allosteric ligand-receptor-transducer complex stability, mediated by conformational dynamics between these sites, in the ultimate determination of affinity, efficacy, cooperativity, probe dependence, and species variability. There results provide a holistic framework for further GPCR mechanistic studies and can aid in the discovery and design of future allosteric drugs.
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Affiliation(s)
- Ziva Vuckovic
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia
| | - Jinan Wang
- Center for Computational Biology and Department of Molecular Biosciences, University of Kansas, Lawrence, United States
| | - Vi Pham
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia
| | - Jesse I Mobbs
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia
- ARC Centre for Cryo-electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia
| | - Matthew J Belousoff
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia
- ARC Centre for Cryo-electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia
| | - Apurba Bhattarai
- Center for Computational Biology and Department of Molecular Biosciences, University of Kansas, Lawrence, United States
| | - Wessel A C Burger
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia
- ARC Centre for Cryo-electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia
| | - Geoff Thompson
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia
| | - Mahmuda Yeasmin
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia
| | - Vindhya Nawaratne
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia
| | - Katie Leach
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia
- ARC Centre for Cryo-electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia
| | - Emma T van der Westhuizen
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia
| | - Elham Khajehali
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia
| | - Yi-Lynn Liang
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia
| | - Alisa Glukhova
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia
- ARC Centre for Cryo-electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia
| | - Denise Wootten
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia
- ARC Centre for Cryo-electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia
| | - Craig W Lindsley
- Department of Pharmacology, Warren Center for Neuroscience Drug Discovery and Department of Chemistry, Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, United States
| | - Andrew Tobin
- The Centre for Translational Pharmacology, Advanced Research Centre (ARC), College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Patrick Sexton
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia
- ARC Centre for Cryo-electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia
| | - Radostin Danev
- Graduate School of Medicine, University of Tokyo, Tokyo, Japan
| | - Celine Valant
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia
| | - Yinglong Miao
- Center for Computational Biology and Department of Molecular Biosciences, University of Kansas, Lawrence, United States
| | - Arthur Christopoulos
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia
- ARC Centre for Cryo-electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia
- Neuromedicines Discovery Centre, Monash University, Parkville, Australia
| | - David M Thal
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia
- ARC Centre for Cryo-electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia
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11
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Heinz CS, Bermudez M, Jaiswal N, Große C, Kauk M, Hoffmann C, Holzgrabe U. Hybridization into a Bitopic Ligand Increased Muscarinic Receptor Activation for Isopilocarpine but Not for Pilocarpine Derivatives. JOURNAL OF NATURAL PRODUCTS 2023; 86:869-881. [PMID: 37042802 DOI: 10.1021/acs.jnatprod.2c01079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Pilocarpine (1), a secondary metabolite of several Pilocarpus species, is a therapeutically used partial agonist of muscarinic acetylcholine receptors (mAChRs). The available pharmacological data and structure-activity relationships do not provide comparable data for all five receptor subtypes. In this study, pilocarpine (1), its epimer isopilocarpine (2), racemic analogues pilosinine (3) and desmethyl pilosinine (4), and the respective hybrid ligands with a naphmethonium fragment (5-C6 to 8-C6) were synthesized and analyzed in mini-G nano-BRET assays at the five mAChRs. In line with earlier studies, pilocarpine was the most active compound among the orthosteric ligands 1-4. Computational docking of pilocarpine and isopilocarpine to the active M2 receptor suggests that the trans-configuration of isopilocarpine leads to a loss of the hydrogen bond from the lactone carbonyl to N6.52, explaining the lower activity of isopilocarpine. Hybrid formation of pilocarpine (1) and isopilocarpine (2) led to an inverted activity rank, with the trans-configured isopilocarpine hybrid (6-C6) being more active. The hydrogen bond of interest is formed by the isopilocarpine hybrid (6-C6) but not by the pilocarpine hybrid (5-C6). Hybridization thus leads to a modified binding mode of the orthosteric moiety, as the binding mode of the hybrid is dominated by the high-affinity allosteric moiety.
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Affiliation(s)
- Christine S Heinz
- Department of Pharmaceutical and Medicinal Chemistry, Institute of Pharmacy, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Marcel Bermudez
- Institute of Pharmaceutical and Medicinal Chemistry, Westfälische Wilhelms-Universität, Corrensstraße 48, 48149 Muenster, Germany
| | - Natasha Jaiswal
- Institute for Molecular Cell Biology, CMB-Center for Molecular Biomedicine, University Hospital Jena, Friedrich-Schiller University Jena, Hans-Knöll-Straße 2, 07745 Jena, Germany
| | - Carolin Große
- Institute for Molecular Cell Biology, CMB-Center for Molecular Biomedicine, University Hospital Jena, Friedrich-Schiller University Jena, Hans-Knöll-Straße 2, 07745 Jena, Germany
| | - Michael Kauk
- Institute for Molecular Cell Biology, CMB-Center for Molecular Biomedicine, University Hospital Jena, Friedrich-Schiller University Jena, Hans-Knöll-Straße 2, 07745 Jena, Germany
| | - Carsten Hoffmann
- Institute for Molecular Cell Biology, CMB-Center for Molecular Biomedicine, University Hospital Jena, Friedrich-Schiller University Jena, Hans-Knöll-Straße 2, 07745 Jena, Germany
| | - Ulrike Holzgrabe
- Department of Pharmaceutical and Medicinal Chemistry, Institute of Pharmacy, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
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12
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Caton S, Dewan A. Olfaction: Allosteric modulation. Curr Biol 2023; 33:R311-R313. [PMID: 37098335 DOI: 10.1016/j.cub.2023.03.046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/27/2023]
Abstract
New research indicates that the odor-evoked responses of human olfactory receptors can be enhanced via the non-competitive binding of an allosteric modulator. This modulatory mechanism adds an additional layer of complexity to the peripheral encoding of odors.
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Affiliation(s)
- Samuel Caton
- Department of Psychology, Program in Neuroscience, Florida State University, Tallahassee, FL 32306, USA
| | - Adam Dewan
- Department of Psychology, Program in Neuroscience, Florida State University, Tallahassee, FL 32306, USA.
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13
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Trimmer C, Arroyave R, Vuilleumier C, Wu L, Dumer A, DeLaura C, Kim J, Pierce GM, Borisovska M, De Nanteuil F, Emberger M, Varganov Y, Margot C, Rogers ME, Pfister P. Allosteric modulation of a human odorant receptor. Curr Biol 2023; 33:1523-1534.e4. [PMID: 36977419 DOI: 10.1016/j.cub.2023.03.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 12/02/2022] [Accepted: 03/06/2023] [Indexed: 03/29/2023]
Abstract
Odor perception is first determined by how the myriad of environmental volatiles are detected at the periphery of the olfactory system. The combinatorial activation of dedicated odorant receptors generates enough encoding power for the discrimination of tens of thousands of odorants. Recent studies have revealed that odorant receptors undergo widespread inhibitory modulation of their activity when presented with mixtures of odorants, a property likely required to maintain discrimination and ensure sparsity of the code for complex mixtures. Here, we establish the role of human OR5AN1 in the detection of musks and identify distinct odorants capable of enhancing its activity in binary mixtures. Chemical and pharmacological characterization indicate that specific α-β unsaturated aliphatic aldehydes act as positive allosteric modulators. Sensory experiments show decreased odor detection threshold in humans, suggesting that allosteric modulation of odorant receptors is perceptually relevant and likely adds another layer of complexity to how odors are encoded in the peripheral olfactory system.
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14
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Do H, Wang J, Miao Y. Deep Learning Dynamic Allostery of G-Protein-Coupled Receptors. RESEARCH SQUARE 2023:rs.3.rs-2543463. [PMID: 36865316 PMCID: PMC9980202 DOI: 10.21203/rs.3.rs-2543463/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
Abstract
G-protein-coupled receptors (GPCRs) are the largest superfamily of human membrane proteins and represent primary targets of ~ 1/3 of currently marketed drugs. Allosteric modulators have emerged as more selective drug candidates compared with orthosteric agonists and antagonists. However, many X-ray and cryo-EM structures of GPCRs resolved so far exhibit negligible differences upon binding of positive and negative allosteric modulators (PAMs and NAMs). Mechanism of dynamic allosteric modulation in GPCRs remains unclear. In this work, we have systematically mapped dynamic changes in free energy landscapes of GPCRs upon binding of allosteric modulators using the Gaussian accelerated molecular dynamics (GaMD), Deep Learning (DL) and free energy prOfiling Workflow (GLOW). A total of 18 available high-resolution experimental structures of allosteric modulator-bound class A and B GPCRs were collected for simulations. A number of 8 computational models were generated to examine selectivity of the modulators by changing their target receptors to different subtypes. All-atom GaMD simulations were performed for a total of 66 μs on 44 GPCR systems in the presence/absence of the modulator. DL and free energy calculations revealed significantly reduced conformational space of GPCRs upon modulator binding. While the modulator-free GPCRs often sampled multiple low-energy conformational states, the NAMs and PAMs confined the inactive and active agonist-G protein-bound GPCRs, respectively, to mostly only one specific conformation for signaling. Such cooperative effects were significantly reduced for binding of the selective modulators to "non-cognate" receptor subtypes in the computational models. Therefore, comprehensive DL of extensive GaMD simulations has revealed a general dynamic mechanism of GPCR allostery, which will greatly facilitate rational design of selective allosteric drugs of GPCRs.
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15
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Shen S, Zhao C, Wu C, Sun S, Li Z, Yan W, Shao Z. Allosteric modulation of G protein-coupled receptor signaling. Front Endocrinol (Lausanne) 2023; 14:1137604. [PMID: 36875468 PMCID: PMC9978769 DOI: 10.3389/fendo.2023.1137604] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Accepted: 01/31/2023] [Indexed: 02/18/2023] Open
Abstract
G protein-coupled receptors (GPCRs), the largest family of transmembrane proteins, regulate a wide array of physiological processes in response to extracellular signals. Although these receptors have proven to be the most successful class of drug targets, their complicated signal transduction pathways (including different effector G proteins and β-arrestins) and mediation by orthosteric ligands often cause difficulties for drug development, such as on- or off-target effects. Interestingly, identification of ligands that engage allosteric binding sites, which are different from classic orthosteric sites, can promote pathway-specific effects in cooperation with orthosteric ligands. Such pharmacological properties of allosteric modulators offer new strategies to design safer GPCR-targeted therapeutics for various diseases. Here, we explore recent structural studies of GPCRs bound to allosteric modulators. Our inspection of all GPCR families reveals recognition mechanisms of allosteric regulation. More importantly, this review highlights the diversity of allosteric sites and presents how allosteric modulators control specific GPCR pathways to provide opportunities for the development of new valuable agents.
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Affiliation(s)
| | | | | | | | | | - Wei Yan
- Division of Nephrology and Kidney Research Institute, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Zhenhua Shao
- Division of Nephrology and Kidney Research Institute, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, China
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16
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Do HN, Wang J, Miao Y. Deep Learning Dynamic Allostery of G-Protein-Coupled Receptors. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.15.524128. [PMID: 36711515 PMCID: PMC9882226 DOI: 10.1101/2023.01.15.524128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
G-protein-coupled receptors (GPCRs) are the largest superfamily of human membrane proteins and represent primary targets of ~1/3 of currently marketed drugs. Allosteric modulators have emerged as more selective drug candidates compared with orthosteric agonists and antagonists. However, many X-ray and cryo-EM structures of GPCRs resolved so far exhibit negligible differences upon binding of positive and negative allosteric modulators (PAMs and NAMs). Mechanism of dynamic allosteric modulation in GPCRs remains unclear. In this work, we have systematically mapped dynamic changes in free energy landscapes of GPCRs upon binding of allosteric modulators using the Gaussian accelerated molecular dynamics (GaMD), Deep Learning (DL) and free energy prOfiling Workflow (GLOW). A total of 18 available high-resolution experimental structures of allosteric modulator-bound class A and B GPCRs were collected for simulations. A number of 8 computational models were generated to examine selectivity of the modulators by changing their target receptors to different subtypes. All-atom GaMD simulations were performed for a total of 66 μs on 44 GPCR systems in the presence/absence of the modulator. DL and free energy calculations revealed significantly reduced conformational space of GPCRs upon modulator binding. While the modulator-free GPCRs often sampled multiple low-energy conformational states, the NAMs and PAMs confined the inactive and active agonist-G protein-bound GPCRs, respectively, to mostly only one specific conformation for signaling. Such cooperative effects were significantly reduced for binding of the selective modulators to "non-cognate" receptor subtypes in the computational models. Therefore, comprehensive DL of extensive GaMD simulations has revealed a general dynamic mechanism of GPCR allostery, which will greatly facilitate rational design of selective allosteric drugs of GPCRs.
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Affiliation(s)
- Hung N. Do
- Center for Computational Biology and Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas 66047
| | - Jinan Wang
- Center for Computational Biology and Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas 66047
| | - Yinglong Miao
- Center for Computational Biology and Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas 66047
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17
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Xu J, Wang Q, Hübner H, Hu Y, Niu X, Wang H, Maeda S, Inoue A, Tao Y, Gmeiner P, Du Y, Jin C, Kobilka BK. Structural and dynamic insights into supra-physiological activation and allosteric modulation of a muscarinic acetylcholine receptor. Nat Commun 2023; 14:376. [PMID: 36690613 PMCID: PMC9870890 DOI: 10.1038/s41467-022-35726-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2022] [Accepted: 12/21/2022] [Indexed: 01/25/2023] Open
Abstract
The M2 muscarinic receptor (M2R) is a prototypical G-protein-coupled receptor (GPCR) that serves as a model system for understanding GPCR regulation by both orthosteric and allosteric ligands. Here, we investigate the mechanisms governing M2R signaling versatility using cryo-electron microscopy (cryo-EM) and NMR spectroscopy, focusing on the physiological agonist acetylcholine and a supra-physiological agonist iperoxo, as well as a positive allosteric modulator LY2119620. These studies reveal that acetylcholine stabilizes a more heterogeneous M2R-G-protein complex than iperoxo, where two conformers with distinctive G-protein orientations were determined. We find that LY2119620 increases the affinity for both agonists, but differentially modulates agonists efficacy in G-protein and β-arrestin pathways. Structural and spectroscopic analysis suggest that LY211620 stabilizes distinct intracellular conformational ensembles from agonist-bound M2R, which may enhance β-arrestin recruitment while impairing G-protein activation. These results highlight the role of conformational dynamics in the complex signaling behavior of GPCRs, and could facilitate design of better drugs.
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Affiliation(s)
- Jun Xu
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, 94305, USA
- Beijing Advanced Innovation Center for Structural Biology, School of Medicine, Tsinghua University, 100084, Beijing, China
| | - Qinggong Wang
- Kobilka Institute of Innovative Drug Discovery, School of Life and Health Sciences, Chinese University of Hong Kong, 518172, Shenzhen, China
- Division of Life Sciences and Medicine, University of Science and Technology of China, 230027, Hefei, P. R. China
| | - Harald Hübner
- Department of Chemistry and Pharmacy, Medicinal Chemistry, Friedrich-Alexander University, 91058, Erlangen, Germany
| | - Yunfei Hu
- Beijing Nuclear Magnetic Resonance Center, College of Chemistry and Molecular Engineering, Peking University, 100084, Beijing, China
- Innovation Academy for Precision Measurement Science and Technology, CAS, 430071, Wuhan, China
| | - Xiaogang Niu
- Beijing Nuclear Magnetic Resonance Center, College of Chemistry and Molecular Engineering, Peking University, 100084, Beijing, China
| | - Haoqing Wang
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - Shoji Maeda
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, 94305, USA
- Department of Pharmacology, Medical School, University of Michigan 1150 Medical Center Dr., 1315 Medical Science Research Bldg III, Ann Arbor, MI, 48109, USA
| | - Asuka Inoue
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, 980-8578, Japan
| | - Yuyong Tao
- Division of Life Sciences and Medicine, University of Science and Technology of China, 230027, Hefei, P. R. China
| | - Peter Gmeiner
- Department of Chemistry and Pharmacy, Medicinal Chemistry, Friedrich-Alexander University, 91058, Erlangen, Germany
| | - Yang Du
- Kobilka Institute of Innovative Drug Discovery, School of Life and Health Sciences, Chinese University of Hong Kong, 518172, Shenzhen, China.
| | - Changwen Jin
- Beijing Nuclear Magnetic Resonance Center, College of Chemistry and Molecular Engineering, Peking University, 100084, Beijing, China.
| | - Brian K Kobilka
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, 94305, USA.
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18
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Papay RS, Macdonald JD, Stauffer SR, Perez DM. Characterization of a novel positive allosteric modulator of the α 1A-Adrenergic receptor. CURRENT RESEARCH IN PHARMACOLOGY AND DRUG DISCOVERY 2022; 4:100142. [PMID: 36544813 PMCID: PMC9762201 DOI: 10.1016/j.crphar.2022.100142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 10/27/2022] [Accepted: 11/15/2022] [Indexed: 12/05/2022] Open
Abstract
α1-Adrenergic Receptors (ARs) are G-protein Coupled Receptors (GPCRs) that regulate the sympathetic nervous system via the binding and activation of norepinephrine (NE) and epinephrine (Epi). α1-ARs control various aspects of neurotransmission, cognition, cardiovascular functions as well as other organ systems. However, therapeutic drug development for these receptors, particularly agonists, has been stagnant due to unwanted effects on blood pressure regulation. We report the synthesis and characterization of the first positive allosteric modulator (PAM) for the α1-AR based upon the derivation of the α1A-AR selective imidazoline agonist, cirazoline. Compound 3 (Cmpd-3) binds the α1A-AR with high and low affinity sites (0.13pM; 54 nM) typical of GPCR agonists, and reverts to a single low affinity site of 100 nM upon the addition of GTP. Comparison of Cmpd-3 versus other orthosteric α1A-AR-selective imidazoline ligands reveal unique properties that are consistent with a type I PAM. Cmpd-3 is both conformationally and ligand-selective for the α1A-AR subtype. In competition binding studies, Cmpd-3 potentiates NE-binding at the α1A-AR only on the high affinity state of NE with no effect on the Epi-bound α1A-AR. Moreover, Cmpd-3 demonstrates signaling-bias and potentiates the NE-mediated cAMP response of the α1A-AR at nM concentrations with no effects on the NE-mediated inositol phosphate response. There are no effects of Cmpd-3 on the signaling at the α1B- or α1D-AR subtypes. Cmpd-3 displays characteristics of a pure PAM with no intrinsic agonist properties. Specific derivation of Cmpd-3 at the R1 ortho-position recapitulated PAM characteristics. Our results characterize the first PAM for the α1-AR and holds promise for a first-in-class therapeutic to treat various diseases without the side effect of increasing blood pressure intrinsic to classical orthosteric agonists.
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Affiliation(s)
- Robert S. Papay
- The Department of Cardiovascular & Metabolic Sciences, Lerner Research Institute, The Cleveland Clinic Foundation, 9500 Euclid Ave, Cleveland, OH, 44195, USA
| | - Jonathan D. Macdonald
- Center for Therapeutics Discovery, Lerner Research Institute, The Cleveland Clinic Foundation, 9500 Euclid Ave, Cleveland, OH, 44195, USA
| | - Shaun R. Stauffer
- Center for Therapeutics Discovery, Lerner Research Institute, The Cleveland Clinic Foundation, 9500 Euclid Ave, Cleveland, OH, 44195, USA
| | - Dianne M. Perez
- The Department of Cardiovascular & Metabolic Sciences, Lerner Research Institute, The Cleveland Clinic Foundation, 9500 Euclid Ave, Cleveland, OH, 44195, USA
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19
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Myslivecek J. Multitargeting nature of muscarinic orthosteric agonists and antagonists. Front Physiol 2022; 13:974160. [PMID: 36148314 PMCID: PMC9486310 DOI: 10.3389/fphys.2022.974160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Accepted: 08/01/2022] [Indexed: 11/16/2022] Open
Abstract
Muscarinic receptors (mAChRs) are typical members of the G protein-coupled receptor (GPCR) family and exist in five subtypes from M1 to M5. Muscarinic receptor subtypes do not sufficiently differ in affinity to orthosteric antagonists or agonists; therefore, the analysis of receptor subtypes is complicated, and misinterpretations can occur. Usually, when researchers mainly specialized in CNS and peripheral functions aim to study mAChR involvement in behavior, learning, spinal locomotor networks, biological rhythms, cardiovascular physiology, bronchoconstriction, gastrointestinal tract functions, schizophrenia, and Parkinson’s disease, they use orthosteric ligands and they do not use allosteric ligands. Moreover, they usually rely on manufacturers’ claims that could be misleading. This review aimed to call the attention of researchers not deeply focused on mAChR pharmacology to this fact. Importantly, limited selective binding is not only a property of mAChRs but is a general attribute of most neurotransmitter receptors. In this review, we want to give an overview of the most common off-targets for established mAChR ligands. In this context, an important point is a mention the tremendous knowledge gap on off-targets for novel compounds compared to very well-established ligands. Therefore, we will summarize reported affinities and give an outline of strategies to investigate the subtype’s function, thereby avoiding ambiguous results. Despite that, the multitargeting nature of drugs acting also on mAChR could be an advantage when treating such diseases as schizophrenia. Antipsychotics are a perfect example of a multitargeting advantage in treatment. A promising strategy is the use of allosteric ligands, although some of these ligands have also been shown to exhibit limited selectivity. Another new direction in the development of muscarinic selective ligands is functionally selective and biased agonists. The possible selective ligands, usually allosteric, will also be listed. To overcome the limited selectivity of orthosteric ligands, the recommended process is to carefully examine the presence of respective subtypes in specific tissues via knockout studies, carefully apply “specific” agonists/antagonists at appropriate concentrations and then calculate the probability of a specific subtype involvement in specific functions. This could help interested researchers aiming to study the central nervous system functions mediated by the muscarinic receptor.
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20
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Wang J, Wu M, Chen Z, Wu L, Wang T, Cao D, Wang H, Liu S, Xu Y, Li F, Liu J, Chen N, Zhao S, Cheng J, Wang S, Hua T. The unconventional activation of the muscarinic acetylcholine receptor M4R by diverse ligands. Nat Commun 2022; 13:2855. [PMID: 35606397 PMCID: PMC9126879 DOI: 10.1038/s41467-022-30595-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Accepted: 05/04/2022] [Indexed: 01/22/2023] Open
Abstract
Muscarinic acetylcholine receptors (mAChRs) respond to the neurotransmitter acetylcholine and play important roles in human nervous system. Muscarinic receptor 4 (M4R) is a promising drug target for treating neurological and mental disorders, such as Alzheimer's disease and schizophrenia. However, the lack of understanding on M4R's activation by subtype selective agonists hinders its therapeutic applications. Here, we report the structural characterization of M4R selective allosteric agonist, compound-110, as well as agonist iperoxo and positive allosteric modulator LY2119620. Our cryo-electron microscopy structures of compound-110, iperoxo or iperoxo-LY2119620 bound M4R-Gi complex reveal their different interaction modes and activation mechanisms of M4R, and the M4R-ip-LY-Gi structure validates the cooperativity between iperoxo and LY2119620 on M4R. Through the comparative structural and pharmacological analysis, compound-110 mostly occupies the allosteric binding pocket with vertical binding pose. Such a binding and activation mode facilitates its allostersic selectivity and agonist profile. In addition, in our schizophrenia-mimic mouse model study, compound-110 shows antipsychotic activity with low extrapyramidal side effects. Thus, this study provides structural insights to develop next-generation antipsychotic drugs selectively targeting on mAChRs subtypes.
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Affiliation(s)
- Jingjing Wang
- iHuman Institute, ShanghaiTech University, 201210, Shanghai, China
| | - Meng Wu
- iHuman Institute, ShanghaiTech University, 201210, Shanghai, China
| | - Zhangcheng Chen
- State Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, 200031, Shanghai, China
| | - Lijie Wu
- iHuman Institute, ShanghaiTech University, 201210, Shanghai, China
| | - Tian Wang
- iHuman Institute, ShanghaiTech University, 201210, Shanghai, China.,School of Life Science and Technology, ShanghaiTech University, 201210, Shanghai, China
| | - Dongmei Cao
- State Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, 200031, Shanghai, China
| | - Huan Wang
- iHuman Institute, ShanghaiTech University, 201210, Shanghai, China
| | - Shenhui Liu
- iHuman Institute, ShanghaiTech University, 201210, Shanghai, China.,School of Life Science and Technology, ShanghaiTech University, 201210, Shanghai, China
| | - Yueming Xu
- iHuman Institute, ShanghaiTech University, 201210, Shanghai, China
| | - Fei Li
- iHuman Institute, ShanghaiTech University, 201210, Shanghai, China
| | - Junlin Liu
- iHuman Institute, ShanghaiTech University, 201210, Shanghai, China
| | - Na Chen
- iHuman Institute, ShanghaiTech University, 201210, Shanghai, China
| | - Suwen Zhao
- iHuman Institute, ShanghaiTech University, 201210, Shanghai, China.,School of Life Science and Technology, ShanghaiTech University, 201210, Shanghai, China
| | - Jianjun Cheng
- iHuman Institute, ShanghaiTech University, 201210, Shanghai, China.
| | - Sheng Wang
- State Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, 200031, Shanghai, China.
| | - Tian Hua
- iHuman Institute, ShanghaiTech University, 201210, Shanghai, China. .,School of Life Science and Technology, ShanghaiTech University, 201210, Shanghai, China.
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21
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Zamora JC, Smith HR, Jennings EM, Chavera TS, Kotipalli V, Jay A, Husbands SM, Disney A, Berg KA, Clarke WP. Long-term antagonism and allosteric regulation of mu opioid receptors by the novel ligand, methocinnamox. Pharmacol Res Perspect 2021; 9:e00887. [PMID: 34713624 PMCID: PMC8554411 DOI: 10.1002/prp2.887] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 09/30/2021] [Indexed: 01/05/2023] Open
Abstract
Opioid overdose is a leading cause of death in the United States. The only treatment available currently is the competitive antagonist, naloxone (Narcan® ). Although naloxone is very effective and has saved many lives, as a competitive antagonist it has limitations. Due to the short half-life of naloxone, renarcotization can occur if the ingested opioid agonist remains in the body longer. Moreover, because antagonism by naloxone is surmountable, renarcotization can also occur in the presence of naloxone if a relatively larger dose of opioid agonist is taken. In such circumstances, a long-lasting, non-surmountable antagonist would offer an improvement in overdose treatment. Methocinnamox (MCAM) has been reported to have a long duration of antagonist action at mu opioid receptors in vivo. In HEK cells expressing the human mu opioid receptor, MCAM antagonism of mu agonist-inhibition of cAMP production was time-dependent, non-surmountable and non-reversible, consistent with (pseudo)-irreversible binding. In vivo, MCAM injected locally into the rat hindpaw antagonized mu agonist-mediated inhibition of thermal allodynia for up to 96 h. By contrast, antagonism by MCAM of delta or kappa agonists in HEK cells and in vivo was consistent with simple competitive antagonism. Surprisingly, MCAM also shifted the concentration-response curves of mu agonists in HEK cells in the absence of receptor reserve in a ligand-dependent manner. The shift in the [D-Ala2 ,N-MePhe4 ,Gly-ol5 ]-enkephalin (DAMGO) concentration-response curve by MCAM was insensitive to naloxone, suggesting that in addition to (pseudo)-irreversible orthosteric antagonism, MCAM acts allosterically to alter the affinity and/or intrinsic efficacy of mu agonists.
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Affiliation(s)
- Joshua C. Zamora
- Department of PharmacologyUT Health San AntonioSan AntonioTexasUSA
| | - Hudson R. Smith
- Department of PharmacologyUT Health San AntonioSan AntonioTexasUSA
| | | | | | - Varun Kotipalli
- Department of PharmacologyUT Health San AntonioSan AntonioTexasUSA
| | - Aleasha Jay
- Department of PharmacologyUT Health San AntonioSan AntonioTexasUSA
| | | | - Alex Disney
- Department of Pharmacy and PharmacologyUniversity of BathBathUnited Kingdom
| | - Kelly A. Berg
- Department of PharmacologyUT Health San AntonioSan AntonioTexasUSA
- Addiction ResearchTreatment & Training Center of ExcellenceUT Health San AntonioSan AntonioTexasUSA
| | - William P. Clarke
- Department of PharmacologyUT Health San AntonioSan AntonioTexasUSA
- Addiction ResearchTreatment & Training Center of ExcellenceUT Health San AntonioSan AntonioTexasUSA
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22
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G protein signaling-biased mu opioid receptor agonists that produce sustained G protein activation are noncompetitive agonists. Proc Natl Acad Sci U S A 2021; 118:2102178118. [PMID: 34819362 DOI: 10.1073/pnas.2102178118] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/13/2021] [Indexed: 12/15/2022] Open
Abstract
The ability of a ligand to preferentially promote engagement of one signaling pathway over another downstream of GPCR activation has been referred to as signaling bias, functional selectivity, and biased agonism. The presentation of ligand bias reflects selectivity between active states of the receptor, which may result in the display of preferential engagement with one signaling pathway over another. In this study, we provide evidence that the G protein-biased mu opioid receptor (MOR) agonists SR-17018 and SR-14968 stabilize the MOR in a wash-resistant yet antagonist-reversible G protein-signaling state. Furthermore, we demonstrate that these structurally related biased agonists are noncompetitive for radiolabeled MOR antagonist binding, and while they stimulate G protein signaling in mouse brains, partial agonists of this class do not compete with full agonist activation. Importantly, opioid antagonists can readily reverse their effects in vivo. Given that chronic treatment with SR-17018 does not lead to tolerance in several mouse pain models, this feature may be desirable for the development of long-lasting opioid analgesics that remain sensitive to antagonist reversal of respiratory suppression.
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23
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Chatzigoulas A, Cournia Z. Rational design of allosteric modulators: Challenges and successes. WIRES COMPUTATIONAL MOLECULAR SCIENCE 2021. [DOI: 10.1002/wcms.1529] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Alexios Chatzigoulas
- Biomedical Research Foundation Academy of Athens Athens Greece
- Department of Informatics and Telecommunications National and Kapodistrian University of Athens Athens Greece
| | - Zoe Cournia
- Biomedical Research Foundation Academy of Athens Athens Greece
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24
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van der Westhuizen ET, Choy KHC, Valant C, McKenzie-Nickson S, Bradley SJ, Tobin AB, Sexton PM, Christopoulos A. Fine Tuning Muscarinic Acetylcholine Receptor Signaling Through Allostery and Bias. Front Pharmacol 2021; 11:606656. [PMID: 33584282 PMCID: PMC7878563 DOI: 10.3389/fphar.2020.606656] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Accepted: 11/30/2020] [Indexed: 12/18/2022] Open
Abstract
The M1 and M4 muscarinic acetylcholine receptors (mAChRs) are highly pursued drug targets for neurological diseases, in particular for Alzheimer's disease and schizophrenia. Due to high sequence homology, selective targeting of any of the M1-M5 mAChRs through the endogenous ligand binding site has been notoriously difficult to achieve. With the discovery of highly subtype selective mAChR positive allosteric modulators in the new millennium, selectivity through targeting an allosteric binding site has opened new avenues for drug discovery programs. However, some hurdles remain to be overcome for these promising new drug candidates to progress into the clinic. One challenge is the potential for on-target side effects, such as for the M1 mAChR where over-activation of the receptor by orthosteric or allosteric ligands can be detrimental. Therefore, in addition to receptor subtype selectivity, a drug candidate may need to exhibit a biased signaling profile to avoid such on-target adverse effects. Indeed, recent studies in mice suggest that allosteric modulators for the M1 mAChR that bias signaling toward specific pathways may be therapeutically important. This review brings together details on the signaling pathways activated by the M1 and M4 mAChRs, evidence of biased agonism at these receptors, and highlights pathways that may be important for developing new subtype selective allosteric ligands to achieve therapeutic benefit.
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Affiliation(s)
- Emma T. van der Westhuizen
- Drug Discovery Biology, Monash Institute for Pharmaceutical Research, Monash University, Parkville, VIC, Australia
| | - K. H. Christopher Choy
- Drug Discovery Biology, Monash Institute for Pharmaceutical Research, Monash University, Parkville, VIC, Australia
| | - Celine Valant
- Drug Discovery Biology, Monash Institute for Pharmaceutical Research, Monash University, Parkville, VIC, Australia
| | - Simon McKenzie-Nickson
- Drug Discovery Biology, Monash Institute for Pharmaceutical Research, Monash University, Parkville, VIC, Australia
| | - Sophie J. Bradley
- Centre for Translational Pharmacology, Institute of Molecular Cell and Systems Biology, University of Glasgow, Glasgow, United Kingdom
| | - Andrew B. Tobin
- Centre for Translational Pharmacology, Institute of Molecular Cell and Systems Biology, University of Glasgow, Glasgow, United Kingdom
| | - Patrick M. Sexton
- Drug Discovery Biology, Monash Institute for Pharmaceutical Research, Monash University, Parkville, VIC, Australia
| | - Arthur Christopoulos
- Drug Discovery Biology, Monash Institute for Pharmaceutical Research, Monash University, Parkville, VIC, Australia
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25
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Birgül Iyison N, Shahraki A, Kahveci K, Düzgün MB, Gün G. Are insect GPCRs ideal next‐generation pesticides: opportunities and challenges. FEBS J 2021; 288:2727-2745. [DOI: 10.1111/febs.15708] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2020] [Revised: 12/27/2020] [Accepted: 01/06/2021] [Indexed: 12/22/2022]
Affiliation(s)
- Necla Birgül Iyison
- Department of Molecular Biology and Genetics Institute of Graduate Studies in Science and Engineering Boğaziçi University Istanbul Turkey
| | - Aida Shahraki
- Department of Molecular Biology and Genetics Institute of Graduate Studies in Science and Engineering Boğaziçi University Istanbul Turkey
| | - Kübra Kahveci
- Department of Molecular Biology and Genetics Institute of Graduate Studies in Science and Engineering Boğaziçi University Istanbul Turkey
| | - Mustafa Barbaros Düzgün
- Department of Molecular Biology and Genetics Institute of Graduate Studies in Science and Engineering Boğaziçi University Istanbul Turkey
| | - Gökhan Gün
- Department of Molecular Biology and Genetics Institute of Graduate Studies in Science and Engineering Boğaziçi University Istanbul Turkey
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26
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Orgován Z, Ferenczy GG, Keserű GM. Allosteric Molecular Switches in Metabotropic Glutamate Receptors. ChemMedChem 2021; 16:81-93. [PMID: 32686363 PMCID: PMC7818470 DOI: 10.1002/cmdc.202000444] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Indexed: 12/22/2022]
Abstract
Metabotropic glutamate receptors (mGlu) are class C G protein-coupled receptors of eight subtypes that are omnipresently expressed in the central nervous system. mGlus have relevance in several psychiatric and neurological disorders, therefore they raise considerable interest as drug targets. Allosteric modulators of mGlus offer advantages over orthosteric ligands owing to their increased potential to achieve subtype selectivity, and this has prompted discovery programs that have produced a large number of reported allosteric mGlu ligands. However, the optimization of allosteric ligands into drug candidates has proved to be challenging owing to induced-fit effects, flat or steep structure-activity relationships and unexpected changes in theirpharmacology. Subtle structural changes identified as molecular switches might modulate the functional activity of allosteric ligands. Here we review these switches discovered in the metabotropic glutamate receptor family..
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Affiliation(s)
- Zoltán Orgován
- Medicinal Chemistry Research GroupResearch Centre for Natural SciencesMagyar tudósok krt. 2Budapest1117Hungary
| | - György G. Ferenczy
- Medicinal Chemistry Research GroupResearch Centre for Natural SciencesMagyar tudósok krt. 2Budapest1117Hungary
| | - György M. Keserű
- Medicinal Chemistry Research GroupResearch Centre for Natural SciencesMagyar tudósok krt. 2Budapest1117Hungary
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27
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Protease-activated receptor-2 ligands reveal orthosteric and allosteric mechanisms of receptor inhibition. Commun Biol 2020; 3:782. [PMID: 33335291 PMCID: PMC7747594 DOI: 10.1038/s42003-020-01504-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Accepted: 11/19/2020] [Indexed: 02/08/2023] Open
Abstract
Protease-activated receptor-2 (PAR2) has been implicated in multiple pathophysiologies but drug discovery is challenging due to low small molecule tractability and a complex activation mechanism. Here we report the pharmacological profiling of a potent new agonist, suggested by molecular modelling to bind in the putative orthosteric site, and two novel PAR2 antagonists with distinctly different mechanisms of inhibition. We identify coupling between different PAR2 binding sites. One antagonist is a competitive inhibitor that binds to the orthosteric site, while a second antagonist is a negative allosteric modulator that binds at a remote site. The allosteric modulator shows probe dependence, more effectively inhibiting peptide than protease activation of PAR2 signalling. Importantly, both antagonists are active in vivo, inhibiting PAR2 agonist-induced acute paw inflammation in rats and preventing activation of mast cells and neutrophils. These results highlight two distinct mechanisms of inhibition that potentially could be targeted for future development of drugs that modulate PAR2. Kennedy et al. report the pharmacological and in vivo profiling of two small molecule PAR2 inhibitors and an agonist. They conclude that while the small molecule agonist and one of the inhibitors bind to the orthosteric PAR2 binding site, the other inhibitor is a negative allosteric modulator, highlighting two distinct mechanisms of inhibition that could be targeted for future development of drugs that modulate PAR2.
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28
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Parthasarathy A, Mantravadi PK, Kalesh K. Detectives and helpers: Natural products as resources for chemical probes and compound libraries. Pharmacol Ther 2020; 216:107688. [PMID: 32980442 DOI: 10.1016/j.pharmthera.2020.107688] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2020] [Revised: 09/20/2020] [Accepted: 09/21/2020] [Indexed: 02/06/2023]
Abstract
About 70% of the drugs in use are derived from natural products, either used directly or in chemically modified form. Among all possible small molecules (not greater than 5 kDa), only a few of them are biologically active. Natural product libraries may have a higher rate of finding "hits" than synthetic libraries, even with the use of fewer compounds. This is due to the complementarity between the "chemical space" of small molecules and biological macromolecules such as proteins, DNA and RNA, in addition to the three-dimensional complexity of NPs. Chemical probes are molecules which aid in the elucidation of the biological mechanisms behind the action of drugs or drug-like molecules by binding with macromolecular/cellular interaction partners. Probe development and application have been spurred by advancements in photoaffinity label synthesis, affinity chromatography, activity based protein profiling (ABPP) and instrumental methods such as cellular thermal shift assay (CETSA) and advanced/hyphenated mass spectrometry (MS) techniques, as well as genome sequencing and bioengineering technologies. In this review, we restrict ourselves to a survey of natural products (including peptides/mini-proteins and excluding antibodies), which have been applied largely in the last 5 years for the target identification of drugs/drug-like molecules used in research on infectious diseases, and the description of their mechanisms of action.
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Affiliation(s)
- Anutthaman Parthasarathy
- Rochester Institute of Technology, Thomas H. Gosnell School of Life Sciences, 85 Lomb Memorial Dr, Rochester, NY 14623, USA
| | | | - Karunakaran Kalesh
- Department of Chemistry, Durham University, Lower Mount Joy, South Road, Durham DH1 3LE, UK.
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29
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Maeda S, Xu J, N Kadji FM, Clark MJ, Zhao J, Tsutsumi N, Aoki J, Sunahara RK, Inoue A, Garcia KC, Kobilka BK. Structure and selectivity engineering of the M 1 muscarinic receptor toxin complex. Science 2020; 369:161-167. [PMID: 32646996 DOI: 10.1126/science.aax2517] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2019] [Accepted: 04/21/2020] [Indexed: 12/13/2022]
Abstract
Muscarinic toxins (MTs) are natural toxins produced by mamba snakes that primarily bind to muscarinic acetylcholine receptors (MAChRs) and modulate their function. Despite their similar primary and tertiary structures, MTs show distinct binding selectivity toward different MAChRs. The molecular details of how MTs distinguish MAChRs are not well understood. Here, we present the crystal structure of M1AChR in complex with MT7, a subtype-selective anti-M1AChR snake venom toxin. The structure reveals the molecular basis of the extreme subtype specificity of MT7 for M1AChR and the mechanism by which it regulates receptor function. Through in vitro engineering of MT7 finger regions that was guided by the structure, we have converted the selectivity from M1AChR toward M2AChR, suggesting that the three-finger fold is a promising scaffold for developing G protein-coupled receptor modulators.
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Affiliation(s)
- Shoji Maeda
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA.
| | - Jun Xu
- Beijing Advanced Innovation Center for Structural Biology, School of Life Science, Tsinghua University, Beijing, China
| | | | - Mary J Clark
- Department of Pharmacology, University of California San Diego School of Medicine, La Jolla, CA 92093, USA
| | - Jiawei Zhao
- Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China
| | - Naotaka Tsutsumi
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA.,Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA.,Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Junken Aoki
- Graduate School of Pharmaceutical Science, Tohoku University, Sendai, Japan
| | - Roger K Sunahara
- Department of Pharmacology, University of California San Diego School of Medicine, La Jolla, CA 92093, USA
| | - Asuka Inoue
- Graduate School of Pharmaceutical Science, Tohoku University, Sendai, Japan
| | - K Christopher Garcia
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA.,Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA.,Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Brian K Kobilka
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA. .,Beijing Advanced Innovation Center for Structural Biology, School of Life Science, Tsinghua University, Beijing, China
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30
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Bartuzi D, Wróbel TM, Kaczor AA, Matosiuk D. Tuning Down the Pain - An Overview of Allosteric Modulation of Opioid Receptors: Mechanisms of Modulation, Allosteric Sites, Modulator Syntheses. Curr Top Med Chem 2020; 20:2852-2865. [PMID: 32479245 DOI: 10.2174/1568026620666200601155451] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 04/16/2020] [Accepted: 04/22/2020] [Indexed: 01/09/2023]
Abstract
Opioid signaling plays a central role in pain perception. As such, it remains the main target in the development of antinociceptive agents, despite serious side effects involved. In recent years, hopes for improved opioid painkillers are rising, together with our understanding of allosterism and biased signaling mechanisms. In this review, we focus on recently discovered allosteric modulators of opioid receptors, insights into phenomena underlying their action, as well as on how they extend our understanding of mechanisms of previously known compounds. A brief overlook of their synthesis is also presented.
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Affiliation(s)
- Damian Bartuzi
- Department of Synthesis and Chemical Technology of Pharmaceutical Substances with Computer Modelling Lab, Medical University of Lublin, Lublin, Poland
| | - Tomasz M Wróbel
- Department of Synthesis and Chemical Technology of Pharmaceutical Substances with Computer Modelling Lab, Medical University of Lublin, Lublin, Poland
| | - Agnieszka A Kaczor
- Department of Synthesis and Chemical Technology of Pharmaceutical Substances with Computer Modelling Lab, Medical University of Lublin, Lublin, Poland
| | - Dariusz Matosiuk
- Department of Synthesis and Chemical Technology of Pharmaceutical Substances with Computer Modelling Lab, Medical University of Lublin, Lublin, Poland
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31
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Jiang C, Amaradhi R, Ganesh T, Dingledine R. An Agonist Dependent Allosteric Antagonist of Prostaglandin EP2 Receptors. ACS Chem Neurosci 2020; 11:1436-1446. [PMID: 32324375 DOI: 10.1021/acschemneuro.0c00078] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
All reported prostaglandin EP2 receptor antagonists have a purely orthosteric, competitive mode of action. Herein, we report the characterization of compound 1 (pubchem CID 664888) as the first EP2 antagonist that features a reversible, agonist dependent allosteric mode of action. Compound 1 displayed an unsurmountable inhibition of cAMP accumulation stimulated by different EP2 agonists in C6 glioma cells overexpressing human EP2 (C6G-hEP2). The degree of reduction of agonist potency and efficacy depended on the agonist employed. Negative allosteric modulation was not observed in C6G cells overexpressing human EP4, IP, or DP1 receptors. Moreover, in the murine microglial cell line that stably expresses human EP2 receptors (BV2-hEP2), compound 1 reduced the EP2 agonist-induced elevation of interleukin 6 (IL-6), IL-1β, and hEP2 mRNA levels and increased that of tumor necrosis factor (TNF)-α. Compound 1 was docked into a homology model of hEP2. The predicted binding site on the cytoplasmic receptor surface was similar to that of allosteric inhibitors of the β2-adrenergic, CC chemokine receptor 9 (CCR9), and CC chemokine receptor 2 (CCR2) receptors, which supports the notion of a conserved G-protein-coupled receptor (GPCR) binding pocket for allosteric inhibitors. As the first agonist dependent negative allosteric modulator of EP2 receptor, the structure of this compound may provide a basis for developing improved allosteric modulators of EP2 receptors.
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Affiliation(s)
- Chunxiang Jiang
- Department of Pharmacology and Chemical Biology, School of Medicine, Emory University, Atlanta, Georgia 30322, United States
- Department of Neurology, The Second Xiangya Hospital of Central South University, Changsha, 410011 Hunan, China
| | - Radhika Amaradhi
- Department of Pharmacology and Chemical Biology, School of Medicine, Emory University, Atlanta, Georgia 30322, United States
| | - Thota Ganesh
- Department of Pharmacology and Chemical Biology, School of Medicine, Emory University, Atlanta, Georgia 30322, United States
| | - Ray Dingledine
- Department of Pharmacology and Chemical Biology, School of Medicine, Emory University, Atlanta, Georgia 30322, United States
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32
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Che T, English J, Krumm BE, Kim K, Pardon E, Olsen RHJ, Wang S, Zhang S, Diberto JF, Sciaky N, Carroll FI, Steyaert J, Wacker D, Roth BL. Nanobody-enabled monitoring of kappa opioid receptor states. Nat Commun 2020; 11:1145. [PMID: 32123179 PMCID: PMC7052193 DOI: 10.1038/s41467-020-14889-7] [Citation(s) in RCA: 78] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Accepted: 02/06/2020] [Indexed: 12/22/2022] Open
Abstract
Recent studies show that GPCRs rapidly interconvert between multiple states although our ability to interrogate, monitor and visualize them is limited by a relative lack of suitable tools. We previously reported two nanobodies (Nb39 and Nb6) that stabilize distinct ligand- and efficacy-delimited conformations of the kappa opioid receptor. Here, we demonstrate via X-ray crystallography a nanobody-targeted allosteric binding site by which Nb6 stabilizes a ligand-dependent inactive state. As Nb39 stabilizes an active-like state, we show how these two state-dependent nanobodies can provide real-time reporting of ligand stabilized states in cells in situ. Significantly, we demonstrate that chimeric GPCRs can be created with engineered nanobody binding sites to report ligand-stabilized states. Our results provide both insights regarding potential mechanisms for allosterically modulating KOR with nanobodies and a tool for reporting the real-time, in situ dynamic range of GPCR activity.
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MESH Headings
- Allosteric Site
- Binding Sites
- Biosensing Techniques
- Crystallography, X-Ray
- Cyclic AMP/metabolism
- Dynorphins/chemistry
- Dynorphins/pharmacology
- HEK293 Cells
- Humans
- Luminescent Measurements/methods
- Piperazines/chemistry
- Piperazines/pharmacology
- Piperidines/chemistry
- Piperidines/pharmacology
- Protein Conformation
- Pyrrolidines/chemistry
- Pyrrolidines/pharmacology
- Receptors, G-Protein-Coupled/chemistry
- Receptors, G-Protein-Coupled/metabolism
- Receptors, Opioid, kappa/agonists
- Receptors, Opioid, kappa/chemistry
- Receptors, Opioid, kappa/genetics
- Receptors, Opioid, kappa/metabolism
- Recombinant Proteins/chemistry
- Recombinant Proteins/genetics
- Recombinant Proteins/metabolism
- Single-Domain Antibodies/chemistry
- Single-Domain Antibodies/metabolism
- Tetrahydroisoquinolines/chemistry
- Tetrahydroisoquinolines/pharmacology
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Affiliation(s)
- Tao Che
- Department of Pharmacology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, USA.
| | - Justin English
- Department of Pharmacology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, USA
| | - Brian E Krumm
- Department of Pharmacology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, USA
| | - Kuglae Kim
- Department of Pharmacology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, USA
| | - Els Pardon
- Structural Biology Brussels, Vrije Universiteit Brussel (VUB), Brussels, 1050, Belgium
- VIB-VUB Center for Structural Biology, VIB, Brussels, 1050, Belgium
| | - Reid H J Olsen
- Department of Pharmacology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, USA
| | - Sheng Wang
- Department of Pharmacology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, USA
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, China
| | - Shicheng Zhang
- Department of Pharmacology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, USA
| | - Jeffrey F Diberto
- Department of Pharmacology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, USA
| | - Noah Sciaky
- Department of Pharmacology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, USA
| | - F Ivy Carroll
- Research Triangle Institute, Research Triangle Park, Durham, NC, USA
| | - Jan Steyaert
- Structural Biology Brussels, Vrije Universiteit Brussel (VUB), Brussels, 1050, Belgium
- VIB-VUB Center for Structural Biology, VIB, Brussels, 1050, Belgium
| | - Daniel Wacker
- Department of Pharmacology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, USA
- Department of Pharmacological Sciences and Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Bryan L Roth
- Department of Pharmacology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, USA.
- Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
- National Institute of Mental Health Psychoactive Drug Screening Program (NIMH PDSP), School of Medicine, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, USA.
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33
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Dal Prà I, Armato U, Chiarini A. Family C G-Protein-Coupled Receptors in Alzheimer's Disease and Therapeutic Implications. Front Pharmacol 2019; 10:1282. [PMID: 31719824 PMCID: PMC6826475 DOI: 10.3389/fphar.2019.01282] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Accepted: 10/07/2019] [Indexed: 12/12/2022] Open
Abstract
Alzheimer’s disease (AD), particularly its sporadic or late-onset form (SAD/LOAD), is the most prevalent (96–98% of cases) neurodegenerative dementia in aged people. AD’s neuropathology hallmarks are intrabrain accumulation of amyloid-β peptides (Aβs) and of hyperphosphorylated Tau (p-Tau) proteins, diffuse neuroinflammation, and progressive death of neurons and oligodendrocytes. Mounting evidences suggest that family C G-protein-coupled receptors (GPCRs), which include γ-aminobutyric acid B receptors (GABABRs), metabotropic glutamate receptors (mGluR1-8), and the calcium-sensing receptor (CaSR), are involved in many neurotransmitter systems that dysfunction in AD. This review updates the available knowledge about the roles of GPCRs, particularly but not exclusively those expressed by brain astrocytes, in SAD/LOAD onset and progression, taking stock of their respective mechanisms of action and of their potential as anti-AD therapeutic targets. In particular, GABABRs prevent Aβs synthesis and neuronal hyperexcitability and group I mGluRs play important pathogenetic roles in transgenic AD-model animals. Moreover, the specific binding of Aβs to the CaSRs of human cortical astrocytes and neurons cultured in vitro engenders a pathological signaling that crucially promotes the surplus synthesis and release of Aβs and hyperphosphorylated Tau proteins, and also of nitric oxide, vascular endothelial growth factor-A, and proinflammatory agents. Concurrently, Aβs•CaSR signaling hinders the release of soluble (s)APP-α peptide, a neurotrophic agent and GABABR1a agonist. Altogether these effects progressively kill human cortical neurons in vitro and likely also in vivo. Several CaSR’s negative allosteric modulators suppress all the noxious effects elicited by Aβs•CaSR signaling in human cortical astrocytes and neurons thus safeguarding neurons’ viability in vitro and raising hopes about their potential therapeutic benefits in AD patients. Further basic and clinical investigations on these hot topics are needed taking always heed that activation of the several brain family C GPCRs may elicit divergent upshots according to the models studied.
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Affiliation(s)
- Ilaria Dal Prà
- Human Histology and Embryology Unit, University of Verona Medical School, Verona, Italy
| | - Ubaldo Armato
- Human Histology and Embryology Unit, University of Verona Medical School, Verona, Italy
| | - Anna Chiarini
- Human Histology and Embryology Unit, University of Verona Medical School, Verona, Italy
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Hollingsworth SA, Kelly B, Valant C, Michaelis JA, Mastromihalis O, Thompson G, Venkatakrishnan AJ, Hertig S, Scammells PJ, Sexton PM, Felder CC, Christopoulos A, Dror RO. Cryptic pocket formation underlies allosteric modulator selectivity at muscarinic GPCRs. Nat Commun 2019; 10:3289. [PMID: 31337749 PMCID: PMC6650467 DOI: 10.1038/s41467-019-11062-7] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Accepted: 06/20/2019] [Indexed: 01/27/2023] Open
Abstract
Allosteric modulators are highly desirable as drugs, particularly for G-protein-coupled receptor (GPCR) targets, because allosteric drugs can achieve selectivity between closely related receptors. The mechanisms by which allosteric modulators achieve selectivity remain elusive, however, particularly given recent structures that reveal similar allosteric binding sites across receptors. Here we show that positive allosteric modulators (PAMs) of the M1 muscarinic acetylcholine receptor (mAChR) achieve exquisite selectivity by occupying a dynamic pocket absent in existing crystal structures. This cryptic pocket forms far more frequently in molecular dynamics simulations of the M1 mAChR than in those of other mAChRs. These observations reconcile mutagenesis data that previously appeared contradictory. Further mutagenesis experiments validate our prediction that preventing cryptic pocket opening decreases the affinity of M1-selective PAMs. Our findings suggest opportunities for the design of subtype-specific drugs exploiting cryptic pockets that open in certain receptors but not in other receptors with nearly identical static structures.
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Affiliation(s)
- Scott A Hollingsworth
- Departments of Computer Science, Molecular and Cellular Physiology, and Structural Biology, and Institute for Computational and Mathematical Engineering, Stanford University, Stanford, CA, 94305, USA
- Merck & Co., Boston, MA, 02110, USA
| | - Brendan Kelly
- Departments of Computer Science, Molecular and Cellular Physiology, and Structural Biology, and Institute for Computational and Mathematical Engineering, Stanford University, Stanford, CA, 94305, USA.
| | - Celine Valant
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, VIC, 3052, Australia
| | - Jordan Arthur Michaelis
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, VIC, 3052, Australia
| | - Olivia Mastromihalis
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, VIC, 3052, Australia
| | - Geoff Thompson
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, VIC, 3052, Australia
| | - A J Venkatakrishnan
- Departments of Computer Science, Molecular and Cellular Physiology, and Structural Biology, and Institute for Computational and Mathematical Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Samuel Hertig
- Departments of Computer Science, Molecular and Cellular Physiology, and Structural Biology, and Institute for Computational and Mathematical Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Peter J Scammells
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, VIC, 3052, Australia
| | - Patrick M Sexton
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, VIC, 3052, Australia
| | - Christian C Felder
- Eli Lilly and Co., Neuroscience, Lilly Corporate Center, Indianapolis, IN, 46285, USA
- Karuna Pharmaceuticals, Inc., South San Francisco, CA, 94080, USA
| | - Arthur Christopoulos
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, VIC, 3052, Australia.
| | - Ron O Dror
- Departments of Computer Science, Molecular and Cellular Physiology, and Structural Biology, and Institute for Computational and Mathematical Engineering, Stanford University, Stanford, CA, 94305, USA.
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35
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Svensson KA, Hao J, Bruns RF. Positive allosteric modulators of the dopamine D1 receptor: A new mechanism for the treatment of neuropsychiatric disorders. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2019; 86:273-305. [PMID: 31378255 DOI: 10.1016/bs.apha.2019.06.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The dopamine D1 receptor plays an important role in motor activity, reward, and cognition. Efforts to develop D1 agonists have been mixed due to poor drug-like properties, tachyphylaxis, and inverted U-shaped dose-response curves. Recently, positive allosteric modulators (PAMs) for the dopamine D1 receptor were discovered and initial pharmacological profiling has suggested that several of the above issues could be addressed with this mechanism. This paper presents an overview of key findings for DETQ (2-(2,6-dichlorophenyl)-1-((1S,3R)-3-(hydroxymethyl)-5-(2-hydroxypropan-2-yl)-1-methyl-3,4-dihydroisoquinolin-2(1H)-yl)ethan-1-one), which is currently the only D1 PAM for which published in vivo data is available. In vitro studies showed selective potentiation of the human D1 receptor without significant allosteric agonist effects. Due to a species difference in affinity for DETQ, transgenic mice expressing the human D1 receptor (hD1 mice) were used in vivo. In contrast to D1 agonists, DETQ increased locomotor activity over a wide dose-range without inverted U-shaped dose response or tachyphylaxis. DETQ also reversed hypo-activity in mice with dopamine depletion due to reserpine pretreatment, suggesting potential for treatment of motor symptoms in Parkinson's disease. Potential pro-cognitive effects were supported by improved performance in the novel object recognition task, enhanced release of cortical acetylcholine and histamine, and increased phosphorylation of the AMPA receptor (GluR1) and the transcription factor CREB. In addition, DETQ enhanced wakefulness in EEG studies and decreased immobility in the forced-swim test. Together, these results provide support for potential utility of D1 PAMs in the treatment of several neuropsychiatric disorders. LY3154207, a close analog of DETQ, is currently in phase 2 clinical trials.
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Affiliation(s)
- Kjell A Svensson
- Neuroscience Discovery, Lilly Research Laboratories, Eli Lilly & Co, Lilly Corporate Center, Indianapolis, IN, United States.
| | - Junliang Hao
- Discovery Chemistry and Research Technologies, Lilly Research Laboratories, Eli Lilly & Co, Lilly Corporate Center, Indianapolis, IN, United States
| | - Robert F Bruns
- Discovery Chemistry and Research Technologies, Lilly Research Laboratories, Eli Lilly & Co, Lilly Corporate Center, Indianapolis, IN, United States
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36
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Mahmod Al-Qattan MN, Mordi MN. Molecular Basis of Modulating Adenosine Receptors Activities. Curr Pharm Des 2019; 25:817-831. [DOI: 10.2174/1381612825666190304122624] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2019] [Accepted: 02/26/2019] [Indexed: 01/04/2023]
Abstract
Modulating cellular processes through extracellular chemical stimuli is medicinally an attractive approach to control disease conditions. GPCRs are the most important group of transmembranal receptors that produce different patterns of activations using intracellular mediators (such as G-proteins and Beta-arrestins). Adenosine receptors (ARs) belong to GPCR class and are divided into A1AR, A2AAR, A2BAR and A3AR. ARs control different physiological activities thus considered valuable target to control neural, heart, inflammatory and other metabolic disorders. Targeting ARs using small molecules essentially works by binding orthosteric and/or allosteric sites of the receptors. Although targeting orthosteric site is considered typical to modulate receptor activity, allosteric sites provide better subtype selectivity, saturable modulation of activity and variable activation patterns. Each receptor exists in dynamical equilibrium between conformational ensembles. The equilibrium is affected by receptor interaction with other molecules. Changing the population of conformational ensembles of the receptor is the method by which orthosteric, allosteric and other cellular components control receptor signaling. Herein, the interactions of ARs with orthosteric, allosteric ligands as well as intracellular mediators are described. A quinary interaction model for the receptor is proposed and energy wells for major conformational ensembles are retrieved.
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Affiliation(s)
| | - Mohd Nizam Mordi
- Centre For Drug Research, Universiti Sains Malaysia, 11800 Gelugor, Penang, Malaysia
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37
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Yang Q, Lachapelle EA, Kablaoui NM, Webb D, Popiolek M, Grimwood S, Kozak R, O’Connor RE, Lazzaro JT, Butler CR, Zhang L. Discovery of Selective M4 Muscarinic Acetylcholine Receptor Agonists with Novel Carbamate Isosteres. ACS Med Chem Lett 2019; 10:941-948. [PMID: 31223452 DOI: 10.1021/acsmedchemlett.9b00106] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Accepted: 05/28/2019] [Indexed: 11/29/2022] Open
Abstract
It has been hypothesized that selective muscarinic acetylcholine receptor (mAChR) M4 subtype activation could provide therapeutic benefits to a number of neurological disorders while minimizing unwanted cholinergic side effects observed due to nonselective mAChR activation. Given the high sequence and structural homology of the orthosteric binding sites among mAChRs, achieving M4 subtype-selective activation has been challenging. Herein, we describe the discovery of a series of M4 subtype-selective agonists bearing novel carbamate isosteres. Comparison of the isosteres' electrostatic potential isosurface sheds light on key structural features for M4 subtype-selective activation. The identified key features were further illustrated in a proposed receptor-agonist interaction mode.
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Affiliation(s)
- Qingyi Yang
- Medicine Design, Pfizer Inc., 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Erik A. Lachapelle
- Medicine Design, Pfizer Inc., 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Natasha M. Kablaoui
- Medicine Design, Pfizer Inc., 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Damien Webb
- Medicine Design, Pfizer Inc., 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Michael Popiolek
- Internal Medicine Research Unit, Pfizer Inc., 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Sarah Grimwood
- Internal Medicine Research Unit, Pfizer Inc., 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Rouba Kozak
- Internal Medicine Research Unit, Pfizer Inc., 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Rebecca E. O’Connor
- Discovery Sciences, Pfizer Inc., 445 Eastern Point Road, Groton, Connecticut 06340, United States
| | - John T. Lazzaro
- Discovery Sciences, Pfizer Inc., 445 Eastern Point Road, Groton, Connecticut 06340, United States
| | - Christopher R. Butler
- Medicine Design, Pfizer Inc., 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Lei Zhang
- Medicine Design, Pfizer Inc., 1 Portland Street, Cambridge, Massachusetts 02139, United States
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38
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Biased agonism and allosteric modulation of metabotropic glutamate receptor 5. Clin Sci (Lond) 2018; 132:2323-2338. [PMID: 30389826 DOI: 10.1042/cs20180374] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Revised: 10/03/2018] [Accepted: 10/05/2018] [Indexed: 12/18/2022]
Abstract
Metabotropic glutamate receptors belong to class C G-protein-coupled receptors and consist of eight subtypes that are ubiquitously expressed throughout the central nervous system. In recent years, the metabotropic glutamate receptor subtype 5 (mGlu5) has emerged as a promising target for a broad range of psychiatric and neurological disorders. Drug discovery programs targetting mGlu5 are primarily focused on development of allosteric modulators that interact with sites distinct from the endogenous agonist glutamate. Significant efforts have seen mGlu5 allosteric modulators progress into clinical trials; however, recent failures due to lack of efficacy or adverse effects indicate a need for a better understanding of the functional consequences of mGlu5 allosteric modulation. Biased agonism is an interrelated phenomenon to allosterism, describing how different ligands acting through the same receptor can differentially influence signaling to distinct transducers and pathways. Emerging evidence demonstrates that allosteric modulators can induce biased pharmacology at the level of intrinsic agonism as well as through differential modulation of orthosteric agonist-signaling pathways. Here, we present key considerations in the discovery and development of mGlu5 allosteric modulators and the opportunities and pitfalls offered by biased agonism and modulation.
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39
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Moo EV, Sexton PM, Christopoulos A, Valant C. Utility of an "Allosteric Site-Impaired" M 2 Muscarinic Acetylcholine Receptor as a Novel Construct for Validating Mechanisms of Action of Synthetic and Putative Endogenous Allosteric Modulators. Mol Pharmacol 2018; 94:1298-1309. [PMID: 30213802 DOI: 10.1124/mol.118.112490] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Accepted: 09/10/2018] [Indexed: 11/22/2022] Open
Abstract
Muscarinic acetylcholine receptors (mAChRs) are exemplar models for understanding G protein-coupled receptor (GPCR) allostery, possessing a "common" allosteric site in an extracellular vestibule (ECV) for synthetic modulators including gallamine, strychnine, and brucine. In addition, there is intriguing evidence of endogenous peptides/proteins that may target this region at the M2 mAChR. A common feature of synthetic and endogenous M2 mAChR negative allosteric modulators (NAMs) is their cationic nature. Using a structure-based approach, we previously designed a mutant M2 mAChR (N410K+T423K) to specifically abrogate binding of ECV cationic modulators (Dror et al., 2013). Herein, we used this "allosteric site-impaired" receptor to investigate allosteric interactions of synthetic modulators as well as basic peptides (poly-l-arginine, endogenously produced protamine, and major basic protein). Using [3H]N-methylscopolamine equilibrium and kinetic binding and functional assays of guanosine 5'-O-[γ-thio]triphosphate [35S] binding and extracellular signal-regulated kinases 1 and 2 phosphorylation, we found modest effects of the mutations on potencies of orthosteric antagonists and an increase in the affinity of the cognate agonist, acetylcholine, likely reflecting the effect of the mutations on the access/egress of these ligands into the orthosteric pocket. More importantly, we noted a significant abrogation in affinity for all synthetic or peptidic modulators at the mutant mAChR, validating their allosteric nature. Collectively, these findings provide evidence for a hitherto-unappreciated role of endogenous cationic peptides interacting allosterically at the M2 mAChR and identify the allosteric site-impaired GPCR as a tool for validating NAM activity as well as a potential candidate for future chemogenetic strategies to understand the physiology of endogenous allosteric substances.
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Affiliation(s)
- Ee Von Moo
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Patrick M Sexton
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Arthur Christopoulos
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Celine Valant
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
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40
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Burger WAC, Sexton PM, Christopoulos A, Thal DM. Toward an understanding of the structural basis of allostery in muscarinic acetylcholine receptors. J Gen Physiol 2018; 150:1360-1372. [PMID: 30190312 PMCID: PMC6168235 DOI: 10.1085/jgp.201711979] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Accepted: 08/14/2018] [Indexed: 01/16/2023] Open
Abstract
Burger et al. summarize our mechanistic understanding of allostery in the prototypical GPCR, the muscarinic acetylcholine receptor. Recent breakthroughs and developments in structural biology have led to a spate of crystal structures for G protein–coupled receptors (GPCRs). This is the case for the muscarinic acetylcholine receptors (mAChRs) where inactive-state structures for four of the five subtypes and two active-state structures for one subtype are available. These mAChR crystal structures have provided new insights into receptor mechanisms, dynamics, and allosteric modulation. This is highly relevant to the mAChRs given that these receptors are an exemplar model system for the study of GPCR allostery. Allosteric mechanisms of the mAChRs are predominantly consistent with a two-state model, albeit with some notable recent exceptions. Herein, we discuss the mechanisms for positive and negative allosteric modulation at the mAChRs and compare and contrast these to evidence offered by pharmacological, biochemical, and computational approaches. This analysis provides insight into the fundamental pharmacological properties exhibited by GPCR allosteric modulators, such as enhanced subtype selectivity, probe dependence, and biased modulation while highlighting the current challenges that remain. Though complex, enhanced molecular understanding of allosteric mechanisms will have considerable influence on our understanding of GPCR activation and signaling and development of therapeutic interventions.
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Affiliation(s)
- Wessel A C Burger
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Patrick M Sexton
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Arthur Christopoulos
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - David M Thal
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
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41
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Wang X, Heinz BA, Qian YW, Carter JH, Gadski RA, Beavers LS, Little SP, Yang CR, Beck JP, Hao J, Schaus JM, Svensson KA, Bruns RF. Intracellular Binding Site for a Positive Allosteric Modulator of the Dopamine D1 Receptor. Mol Pharmacol 2018; 94:1232-1245. [DOI: 10.1124/mol.118.112649] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Accepted: 08/10/2018] [Indexed: 01/08/2023] Open
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42
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Khajehali E, Valant C, Jörg M, Tobin AB, Conn PJ, Lindsley CW, Sexton PM, Scammells PJ, Christopoulos A. Probing the binding site of novel selective positive allosteric modulators at the M 1 muscarinic acetylcholine receptor. Biochem Pharmacol 2018; 154:243-254. [PMID: 29777683 PMCID: PMC6066355 DOI: 10.1016/j.bcp.2018.05.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Accepted: 05/15/2018] [Indexed: 12/12/2022]
Abstract
Subtype-selective allosteric modulation of the M1 muscarinic acetylcholine (ACh) receptor (M1 mAChR) is an attractive approach for the treatment of numerous disorders, including cognitive deficits. The discovery of benzyl quinolone carboxylic acid, BQCA, a selective M1 mAChR positive allosteric modulator (PAM), spurred the subsequent development of newer generation M1 PAMs representing diverse chemical scaffolds, different pharmacodynamic properties and, in some instances, improved pharmacokinetics. Key exemplar molecules from such efforts include PF-06767832 (N-((3R,4S)-3-hydroxytetrahydro-2H-pyran-4-yl)-5-methyl-4-(4-(thiazol-4-yl)benzyl)pyridine-2-carboxamide), VU6004256 (4,6-difluoro-N-(1S,2S)-2-hydroxycyclohexyl-1-((6-(1-methyl-1H-pyrazol-4-yl)pyridine-3-yl)methyl)-1H-indole-3-carboxamide) and MIPS1780 (3-(2-hydroxycyclohexyl)-6-(2-((4-(1-methyl-1H-pyrazol-4-yl)-benzyl)oxy)phenyl)pyrimidin-4(3H)-one). Given these diverse scaffolds and pharmacodynamics, the current study combined pharmacological analysis and site-directed mutagenesis to explore the potential binding site and function of newer M1 mAChR PAMs relative to BQCA. Interestingly, the mechanism of action of the novel PAMs was consistent with a common model of allostery, as previously described for BQCA. Key residues involved in the activity of BQCA, including Y179 in the second extracellular loop (ECL) and W4007.35 in transmembrane domain (TM) 7, were critical for the activity of all PAMs tested. Overall, our data indicate that structurally distinct PAMs share a similar binding site with BQCA, specifically, an extracellular allosteric site defined by residues in TM2, TM7 and ECL2. These findings provide valuable insights into the structural basis underlying modulator binding, cooperativity and signaling at the M1 mAChR, which is essential for the rational design of PAMs with tailored pharmacological properties.
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Affiliation(s)
- Elham Khajehali
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
| | - Celine Valant
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
| | - Manuela Jörg
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
| | - Andrew B Tobin
- Centre for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - P Jeffrey Conn
- Department of Chemistry, Department of Pharmacology, Vanderbilt Center for Neuroscience Drug Discovery, Nashville, TN 37232, United States
| | - Craig W Lindsley
- Department of Chemistry, Department of Pharmacology, Vanderbilt Center for Neuroscience Drug Discovery, Nashville, TN 37232, United States
| | - Patrick M Sexton
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
| | - Peter J Scammells
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
| | - Arthur Christopoulos
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia.
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Berizzi AE, Bender AM, Lindsley CW, Conn PJ, Sexton PM, Langmead CJ, Christopoulos A. Structure-Activity Relationships of Pan-Gα q/11 Coupled Muscarinic Acetylcholine Receptor Positive Allosteric Modulators. ACS Chem Neurosci 2018; 9:1818-1828. [PMID: 29683647 DOI: 10.1021/acschemneuro.8b00136] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Recent years have seen a large increase in the discovery of allosteric ligands targeting muscarinic acetylcholine receptors (mAChRs). One of the challenges in screening such compounds is to understand their mechanisms of action and define appropriate parameter estimates for affinity, cooperativity and efficacy. Herein we describe the mechanisms of action and structure-activity relationships for a series of "pan-Gq-coupled" muscarinic acetylcholine (ACh) receptor (mAChR) positive allosteric modulators (PAMs). Using a combination of radioligand binding, functional inositol phosphate accumulation assays, receptor alkylation and operational data analysis, we show that most compounds in the series derive their variable potency and selectivity from differential cooperativity at the M1, M3 and M5 mAChRs. None of the PAMs showed greater than 10-fold subtype selectivity for the agonist-free receptor, but VU6007705, VU6007678, and VU6008555 displayed markedly increased cooperativity compared to the parent molecule and M5 mAChR-preferring PAM, ML380 (αβ > 100), in the presence of ACh. Most of the activity of these PAMs derives from their ability to potentiate ACh binding affinity at mAChRs, though VU6007678 was notable for also potentiating ACh signaling efficacy and robust allosteric agonist activity. These data provide key insights for the future design of more potent and subtype-selective mAChR PAMs.
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Affiliation(s)
- Alice E. Berizzi
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Aaron M. Bender
- Departments of Pharmacology & Chemistry, Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Craig W. Lindsley
- Departments of Pharmacology & Chemistry, Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - P. Jeffrey Conn
- Departments of Pharmacology & Chemistry, Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Patrick M. Sexton
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Christopher J. Langmead
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Arthur Christopoulos
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
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van der Westhuizen ET, Spathis A, Khajehali E, Jörg M, Mistry SN, Capuano B, Tobin AB, Sexton PM, Scammells PJ, Valant C, Christopoulos A. Assessment of the Molecular Mechanisms of Action of Novel 4-Phenylpyridine-2-One and 6-Phenylpyrimidin-4-One Allosteric Modulators at the M 1 Muscarinic Acetylcholine Receptors. Mol Pharmacol 2018; 94:770-783. [PMID: 29691279 PMCID: PMC7616191 DOI: 10.1124/mol.118.111633] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Accepted: 04/18/2018] [Indexed: 12/28/2022] Open
Abstract
Positive allosteric modulators (PAMs) that target the M1 muscarinic acetylcholine (ACh) receptor (M1 mAChR) are potential treatments for cognitive deficits in conditions such as Alzheimer disease and schizophrenia. We recently reported novel 4-phenylpyridine-2-one and 6-phenylpyrimidin-4-one M1 mAChR PAMs with the potential to display different modes of positive allosteric modulation and/or agonism but whose molecular mechanisms of action remain undetermined. The current study compared the pharmacology of three such novel PAMs with the prototypical first-generation PAM, benzyl quinolone carboxylic acid (BQCA), in a recombinant Chinese hamster ovary (CHO) cell line stably expressing the human M1 mAChR. Interactions between the orthosteric agonists and the novel PAMs or BQCA suggested their allosteric effects were solely governed by modulation of agonist affinity. The greatest degree of positive co-operativity was observed with higher efficacy agonists, whereas minimal potentiation was observed when the modulators were tested against the lower efficacy agonist, xanomeline. Each PAM was investigated for its effects on the endogenous agonist ACh on three different signaling pathways [extracellular signal-regulated kinases 1/2 phosphorylation, inositol monophosphate (IP1) accumulation, and β-arrestin-2 recruitment], revealing that the allosteric potentiation generally tracked with the efficiency of stimulus-response coupling, and that there was little pathway bias in the allosteric effects. Thus, despite the identification of novel allosteric scaffolds targeting the M1 mAChR, the molecular mechanism of action of these compounds is largely consistent with a model of allostery previously described for BQCA, suggesting that this may be a more generalized mechanism for M1 mAChR PAM effects than previously appreciated.
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Affiliation(s)
- Emma T van der Westhuizen
- Drug Discovery Biology (E.T.W., A.S., E.K., P.M.S., C.V., A.C.) and Medicinal Chemistry (M.J., S.N.M., B.C., P.J.S.), Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia; and Centre for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom (A.B.T.)
| | - Arthur Spathis
- Drug Discovery Biology (E.T.W., A.S., E.K., P.M.S., C.V., A.C.) and Medicinal Chemistry (M.J., S.N.M., B.C., P.J.S.), Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia; and Centre for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom (A.B.T.)
| | - Elham Khajehali
- Drug Discovery Biology (E.T.W., A.S., E.K., P.M.S., C.V., A.C.) and Medicinal Chemistry (M.J., S.N.M., B.C., P.J.S.), Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia; and Centre for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom (A.B.T.)
| | - Manuela Jörg
- Drug Discovery Biology (E.T.W., A.S., E.K., P.M.S., C.V., A.C.) and Medicinal Chemistry (M.J., S.N.M., B.C., P.J.S.), Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia; and Centre for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom (A.B.T.)
| | - Shailesh N Mistry
- Drug Discovery Biology (E.T.W., A.S., E.K., P.M.S., C.V., A.C.) and Medicinal Chemistry (M.J., S.N.M., B.C., P.J.S.), Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia; and Centre for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom (A.B.T.)
| | - Ben Capuano
- Drug Discovery Biology (E.T.W., A.S., E.K., P.M.S., C.V., A.C.) and Medicinal Chemistry (M.J., S.N.M., B.C., P.J.S.), Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia; and Centre for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom (A.B.T.)
| | - Andrew B Tobin
- Drug Discovery Biology (E.T.W., A.S., E.K., P.M.S., C.V., A.C.) and Medicinal Chemistry (M.J., S.N.M., B.C., P.J.S.), Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia; and Centre for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom (A.B.T.)
| | - Patrick M Sexton
- Drug Discovery Biology (E.T.W., A.S., E.K., P.M.S., C.V., A.C.) and Medicinal Chemistry (M.J., S.N.M., B.C., P.J.S.), Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia; and Centre for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom (A.B.T.)
| | - Peter J Scammells
- Drug Discovery Biology (E.T.W., A.S., E.K., P.M.S., C.V., A.C.) and Medicinal Chemistry (M.J., S.N.M., B.C., P.J.S.), Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia; and Centre for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom (A.B.T.)
| | - Celine Valant
- Drug Discovery Biology (E.T.W., A.S., E.K., P.M.S., C.V., A.C.) and Medicinal Chemistry (M.J., S.N.M., B.C., P.J.S.), Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia; and Centre for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom (A.B.T.)
| | - Arthur Christopoulos
- Drug Discovery Biology (E.T.W., A.S., E.K., P.M.S., C.V., A.C.) and Medicinal Chemistry (M.J., S.N.M., B.C., P.J.S.), Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia; and Centre for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom (A.B.T.)
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Vecchio EA, Baltos JA, Nguyen ATN, Christopoulos A, White PJ, May LT. New paradigms in adenosine receptor pharmacology: allostery, oligomerization and biased agonism. Br J Pharmacol 2018; 175:4036-4046. [PMID: 29679502 DOI: 10.1111/bph.14337] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Revised: 03/29/2018] [Accepted: 04/04/2018] [Indexed: 12/17/2022] Open
Abstract
Adenosine receptors are a family of GPCRs containing four subtypes (A1 , A2A , A2B and A3 receptors), all of which bind the ubiquitous nucleoside adenosine. These receptors play an important role in physiology and pathophysiology and therefore represent attractive drug targets for a range of conditions. The theoretical framework surrounding drug action at adenosine receptors now extends beyond the notion of prototypical agonism and antagonism to encompass more complex pharmacological concepts. New paradigms include allostery, in which ligands bind a topographically distinct receptor site from that of the endogenous agonist, homomeric or heteromeric interactions across receptor oligomers and biased agonism, that is, ligand-dependent differential intracellular signalling. This review provides a concise overview of allostery, oligomerization and biased agonism at adenosine receptors and outlines how these paradigms may enhance future drug discovery endeavours focussed on the development of novel therapeutic agents acting at adenosine receptors. LINKED ARTICLES This article is part of a themed section on Molecular Pharmacology of GPCRs. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.21/issuetoc.
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Affiliation(s)
- Elizabeth A Vecchio
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Melbourne, VIC, Australia.,Department of Pharmacology, Monash University, Melbourne, VIC, Australia
| | - Jo-Anne Baltos
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Melbourne, VIC, Australia.,Department of Pharmacology, Monash University, Melbourne, VIC, Australia
| | - Anh T N Nguyen
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Melbourne, VIC, Australia.,Department of Pharmacology, Monash University, Melbourne, VIC, Australia
| | - Arthur Christopoulos
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Melbourne, VIC, Australia.,Department of Pharmacology, Monash University, Melbourne, VIC, Australia
| | - Paul J White
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Melbourne, VIC, Australia
| | - Lauren T May
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Melbourne, VIC, Australia.,Department of Pharmacology, Monash University, Melbourne, VIC, Australia
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Diepenhorst NA, Leach K, Keller AN, Rueda P, Cook AE, Pierce TL, Nowell C, Pastoureau P, Sabatini M, Summers RJ, Charman WN, Sexton PM, Christopoulos A, Langmead CJ. Divergent effects of strontium and calcium-sensing receptor positive allosteric modulators (calcimimetics) on human osteoclast activity. Br J Pharmacol 2018; 175:4095-4108. [PMID: 29714810 DOI: 10.1111/bph.14344] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Revised: 02/06/2018] [Accepted: 04/17/2018] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND AND PURPOSE Strontium ranelate, a drug approved and until recently used for the treatment of osteoporosis, mediates its effects on bone at least in part via the calcium-sensing (CaS) receptor. However, it is not known whether bone-targeted CaS receptor positive allosteric modulators (PAMs; calcimimetics) represent an alternative (or adjunctive) therapy to strontium (Sr2+ o ). EXPERIMENTAL APPROACH We assessed three structurally distinct calcimimetics [cinacalcet, AC-265347 and a benzothiazole tri-substituted urea (BTU-compound 13)], alone and in combination with extracellular calcium (Ca2+ o ) or Sr2+ o , in G protein-dependent signalling assays and trafficking experiments in HEK293 cells and their effects on cell differentiation, tartrate-resistant acid phosphatase (TRAP) activity and hydroxyapatite resorption assays in human blood-derived osteoclasts. KEY RESULTS Sr2+ o activated CaS receptor-dependent signalling in HEK293 cells in a similar manner to Ca2+ o , and inhibited the maturation, TRAP expression and hydroxyapatite resorption capacity of human osteoclasts. Calcimimetics potentiated Ca2+ o - and Sr2+ o -mediated CaS receptor signalling in HEK293 cells with distinct biased profiles, and only cinacalcet chaperoned an endoplasmic reticulum-retained CaS mutant receptor to the cell surface in HEK293 cells, indicative of a conformational state different from that engendered by AC-265347 and BTU-compound 13. Intriguingly, only cinacalcet modulated human osteoclast function, reducing TRAP activity and profoundly inhibiting resorption. CONCLUSION AND IMPLICATIONS Although AC-265347 and BTU-compound 13 potentiated Ca2+ o - and Sr2+ o -induced CaS receptor activation, they neither replicated nor potentiated the ability of Sr2+ o to inhibit human osteoclast function. In contrast, the FDA-approved calcimimetic, cinacalcet, inhibited osteoclast TRAP activity and hydroxyapatite resorption, which may contribute to its clinical effects on bone mineral density LINKED ARTICLES: This article is part of a themed section on Molecular Pharmacology of GPCRs. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.21/issuetoc.
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Affiliation(s)
- Natalie A Diepenhorst
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
| | - Katie Leach
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
| | - Andrew N Keller
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
| | - Patricia Rueda
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
| | - Anna E Cook
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
| | - Tracie L Pierce
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
| | - Cameron Nowell
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
| | | | | | - Roger J Summers
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
| | - William N Charman
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
| | - Patrick M Sexton
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
| | - Arthur Christopoulos
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
| | - Christopher J Langmead
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
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Hellyer SD, Albold S, Wang T, Chen ANY, May LT, Leach K, Gregory KJ. “Selective” Class C G Protein-Coupled Receptor Modulators Are Neutral or Biased mGlu5 Allosteric Ligands. Mol Pharmacol 2018. [DOI: 10.1124/mol.117.111518] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
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Structure-based discovery of selective positive allosteric modulators of antagonists for the M 2 muscarinic acetylcholine receptor. Proc Natl Acad Sci U S A 2018; 115:E2419-E2428. [PMID: 29453275 PMCID: PMC5877965 DOI: 10.1073/pnas.1718037115] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The orthosteric binding sites of the five muscarinic acetylcholine receptor (mAChR) subtypes are highly conserved, making the development of selective antagonists challenging. The allosteric sites of these receptors are more variable, allowing one to imagine allosteric modulators that confer subtype selectivity, which would reduce the major off-target effects of muscarinic antagonists. Accordingly, a large library docking campaign was prosecuted seeking unique positive allosteric modulators (PAMs) for antagonists, ultimately revealing a PAM that substantially potentiates antagonist binding leading to subtype selectivity at the M2 mAChR. This study supports the feasibility of discovering PAMs that can convert an armamentarium of potent but nonselective G-protein–coupled receptor (GPCR) antagonist drugs into subtype-selective reagents. Subtype-selective antagonists for muscarinic acetylcholine receptors (mAChRs) have long been elusive, owing to the highly conserved orthosteric binding site. However, allosteric sites of these receptors are less conserved, motivating the search for allosteric ligands that modulate agonists or antagonists to confer subtype selectivity. Accordingly, a 4.6 million-molecule library was docked against the structure of the prototypical M2 mAChR, seeking molecules that specifically stabilized antagonist binding. This led us to identify a positive allosteric modulator (PAM) that potentiated the antagonist N-methyl scopolamine (NMS). Structure-based optimization led to compound ’628, which enhanced binding of NMS, and the drug scopolamine itself, with a cooperativity factor (α) of 5.5 and a KB of 1.1 μM, while sparing the endogenous agonist acetylcholine. NMR spectral changes determined for methionine residues reflected changes in the allosteric network. Moreover, ’628 slowed the dissociation rate of NMS from the M2 mAChR by 50-fold, an effect not observed at the other four mAChR subtypes. The specific PAM effect of ’628 on NMS antagonism was conserved in functional assays, including agonist stimulation of [35S]GTPγS binding and ERK 1/2 phosphorylation. Importantly, the selective allostery between ’628 and NMS was retained in membranes from adult rat hypothalamus and in neonatal rat cardiomyocytes, supporting the physiological relevance of this PAM/antagonist approach. This study supports the feasibility of discovering PAMs that confer subtype selectivity to antagonists; molecules like ’628 can convert an armamentarium of potent but nonselective GPCR antagonist drugs into subtype-selective reagents, thus reducing their off-target effects.
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Current status of muscarinic M1 and M4 receptors as drug targets for neurodegenerative diseases. Neuropharmacology 2018; 136:449-458. [PMID: 29374561 DOI: 10.1016/j.neuropharm.2018.01.028] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Revised: 01/09/2018] [Accepted: 01/21/2018] [Indexed: 01/17/2023]
Abstract
The cholinergic signalling system has been an attractive pathway to seek targets for modulation of arousal, cognition, and attention which are compromised in neurodegenerative and neuropsychiatric diseases. The acetylcholine muscarinic receptor M1 and M4 subtypes which are highly expressed in the central nervous system, in cortex, hippocampus and striatum, key areas of cognitive and neuropsychiatric control, have received particular attention. Historical muscarinic drug development yielded first generation agonists with modest selectivity for these two receptor targets over M2 and M3 receptors, the major peripheral sub-types hypothesised to underlie the dose-limiting clinical side effects. More recent compound screening and medicinal chemistry optimization of orthosteric and allosteric agonists, and positive allosteric modulators binding to sites distinct from the highly homologous acetylcholine binding pocket have yielded a collection of highly selective tool compounds for preclinical validation studies. Several M1 selective ligands have progressed to early clinical development and in time will hopefully lead to useful therapeutics for treating symptoms of Alzheimer's disease and related disorders. This article is part of the Special Issue entitled 'Neuropharmacology on Muscarinic Receptors'.
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Abstract
From the pharmacological point of view, allosteric modulators may present numerous advantages over orthosteric ligands. Growing availability of novel tools and experimental data provides a tempting opportunity to apply computational methods to improve known modulators and design novel ones. However, recent progress in understanding of complexity of allostery increases awareness of problems involved in design of modulators with desired properties. Deeper insight into phenomena such as probe dependence, altering signaling bias with minor changes in ligand structure, as well as influence of subtle endogenous allosteric factors turns out to be fundamental. These effects make the design of a modulator with precise pharmacological outcome a very challenging task, and need to be taken into consideration throughout the design process. In this chapter, we focus on nuances of targeting GPCR allosteric sites in computational drug design efforts, in particular with application of docking, virtual screening, and molecular dynamics.
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