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Gallagher CI, Ha DA, Harvey RJ, Vandenberg RJ. Positive Allosteric Modulators of Glycine Receptors and Their Potential Use in Pain Therapies. Pharmacol Rev 2022; 74:933-961. [PMID: 36779343 PMCID: PMC9553105 DOI: 10.1124/pharmrev.122.000583] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2022] [Revised: 04/26/2022] [Accepted: 05/13/2022] [Indexed: 11/22/2022] Open
Abstract
Glycine receptors are ligand-gated ion channels that mediate synaptic inhibition throughout the mammalian spinal cord, brainstem, and higher brain regions. They have recently emerged as promising targets for novel pain therapies due to their ability to produce antinociception by inhibiting nociceptive signals within the dorsal horn of the spinal cord. This has greatly enhanced the interest in developing positive allosteric modulators of glycine receptors. Several pharmaceutical companies and research facilities have attempted to identify new therapeutic leads by conducting large-scale screens of compound libraries, screening new derivatives from natural sources, or synthesizing novel compounds that mimic endogenous compounds with antinociceptive activity. Advances in structural techniques have also led to the publication of multiple high-resolution structures of the receptor, highlighting novel allosteric binding sites and providing additional information for previously identified binding sites. This has greatly enhanced our understanding of the functional properties of glycine receptors and expanded the structure activity relationships of novel pharmacophores. Despite this, glycine receptors are yet to be used as drug targets due to the difficulties in obtaining potent, selective modulators with favorable pharmacokinetic profiles that are devoid of side effects. This review presents a summary of the structural basis for how current compounds cause positive allosteric modulation of glycine receptors and discusses their therapeutic potential as analgesics. SIGNIFICANCE STATEMENT: Chronic pain is a major cause of disability, and in Western societies, this will only increase as the population ages. Despite the high level of prevalence and enormous socioeconomic burden incurred, treatment of chronic pain remains limited as it is often refractory to current analgesics, such as opioids. The National Institute for Drug Abuse has set finding effective, safe, nonaddictive strategies to manage chronic pain as their top priority. Positive allosteric modulators of glycine receptors may provide a therapeutic option.
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Affiliation(s)
- Casey I Gallagher
- Molecular Biomedicine, School of Medical Sciences, University of Sydney, Sydney, Australia (C.I.G., D.A.H., R.J.V.) and Biomedical Science, School of Health and Behavioural Sciences and Sunshine Coast Health Institute, University of the Sunshine Coast, Maroochydore, Australia (R.J.H.)
| | - Damien A Ha
- Molecular Biomedicine, School of Medical Sciences, University of Sydney, Sydney, Australia (C.I.G., D.A.H., R.J.V.) and Biomedical Science, School of Health and Behavioural Sciences and Sunshine Coast Health Institute, University of the Sunshine Coast, Maroochydore, Australia (R.J.H.)
| | - Robert J Harvey
- Molecular Biomedicine, School of Medical Sciences, University of Sydney, Sydney, Australia (C.I.G., D.A.H., R.J.V.) and Biomedical Science, School of Health and Behavioural Sciences and Sunshine Coast Health Institute, University of the Sunshine Coast, Maroochydore, Australia (R.J.H.)
| | - Robert J Vandenberg
- Molecular Biomedicine, School of Medical Sciences, University of Sydney, Sydney, Australia (C.I.G., D.A.H., R.J.V.) and Biomedical Science, School of Health and Behavioural Sciences and Sunshine Coast Health Institute, University of the Sunshine Coast, Maroochydore, Australia (R.J.H.)
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Zhang Y, Wang K, Yu Z. Drug Development in Channelopathies: Allosteric Modulation of Ligand-Gated and Voltage-Gated Ion Channels. J Med Chem 2020; 63:15258-15278. [PMID: 33253554 DOI: 10.1021/acs.jmedchem.0c01304] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Ion channels have been characterized as promising drug targets for treatment of numerous human diseases. Functions of ion channels can be fine-tuned by allosteric modulators, which interact with channels and modulate their activities by binding to sites spatially discrete from those of orthosteric ligands. Positive and negative allosteric modulators have presented a plethora of potential therapeutic advantages over traditionally orthosteric agonists and antagonists in terms of selectivity and safety. This thematic review highlights the discovery of representative allosteric modulators for ligand-gated and voltage-gated ion channels, discussing in particular their identifications, locations, and therapeutic uses in the treatment of a range of channelopathies. Additionally, structures and functions of selected ion channels are briefly described to aid in the rational design of channel modulators. Overall, allosteric modulation represents an innovative targeting approach, and the corresponding modulators provide an abundant but challenging landscape for novel therapeutics targeting ligand-gated and voltage-gated ion channels.
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Affiliation(s)
- Yanyun Zhang
- Department of Medicinal Chemistry, School of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, Shandong 250012, China
| | - Ke Wang
- Department of Medicinal Chemistry, School of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, Shandong 250012, China
| | - Zhiyi Yu
- Department of Medicinal Chemistry, School of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, Shandong 250012, China
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Kocyła A, Tran JB, Krężel A. Galvanization of Protein-Protein Interactions in a Dynamic Zinc Interactome. Trends Biochem Sci 2020; 46:64-79. [PMID: 32958327 DOI: 10.1016/j.tibs.2020.08.011] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2020] [Revised: 08/10/2020] [Accepted: 08/19/2020] [Indexed: 02/06/2023]
Abstract
The presence of Zn2+ at protein-protein interfaces modulates complex function, stability, and introduces structural flexibility/complexity, chemical selectivity, and reversibility driven in a Zn2+-dependent manner. Recent studies have demonstrated that dynamically changing Zn2+ affects numerous cellular processes, including protein-protein communication and protein complex assembly. How Zn2+-involved protein-protein interactions (ZPPIs) are formed and dissociate and how their stability and reactivity are driven in a zinc interactome remain poorly understood, mostly due to experimental obstacles. Here, we review recent research advances on the role of Zn2+ in the formation of interprotein sites, their architecture, function, and stability. Moreover, we underline the importance of zinc networks in intersystemic communication and highlight bioinformatic and experimental challenges required for the identification and investigation of ZPPIs.
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Affiliation(s)
- Anna Kocyła
- Department of Chemical Biology, Faculty of Biotechnology, University of Wrocław, Joliot-Curie 14a, 50-383 Wrocław, Poland
| | - Józef Ba Tran
- Department of Chemical Biology, Faculty of Biotechnology, University of Wrocław, Joliot-Curie 14a, 50-383 Wrocław, Poland
| | - Artur Krężel
- Department of Chemical Biology, Faculty of Biotechnology, University of Wrocław, Joliot-Curie 14a, 50-383 Wrocław, Poland.
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Identification of N-acyl amino acids that are positive allosteric modulators of glycine receptors. Biochem Pharmacol 2020; 180:114117. [PMID: 32579961 DOI: 10.1016/j.bcp.2020.114117] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 06/16/2020] [Accepted: 06/18/2020] [Indexed: 01/31/2023]
Abstract
Glycine receptors (GlyRs) mediate inhibitory neurotransmission within the spinal cord and play a crucial role in nociceptive signalling. This makes them primary targets for the development of novel chronic pain therapies. Endogenous lipids have previously been shown to modulate glycine receptors and produce analgesia in pain models, however little is known about what chemical features mediate these effects. In this study, we characterised lipid modulation of GlyRs by screening a library of N-acyl amino acids across all receptor subtypes and determined chemical features crucial for their activity. Acyl-glycine's with a C18 carbon tail were found to produce the greatest potentiation, and require a cis double bond within the central region of the carbon tail (ω6 - ω9) to be active. At 1 µM, C18 ω6,9 glycine potentiated glycine induced currents in α3 and α3β receptors by over 50%, and α1, α2, α1β and α2β receptors by over 100%. C18 ω9 glycine (N-oleoyl glycine) significantly enhance glycine induced peak currents and cause a dose-dependent shift in the glycine concentration response. In the presence of 3 µM C18 ω9 glycine, the EC5o of glycine at the α1 receptor was reduced from 17 µM to 10 µM. This study has identified several acyl-amino acids which are positive allosteric modulators of GlyRs and make promising lead compounds for the development of novel chronic pain therapies.
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Pflanz NC, Daszkowski AW, James KA, Mihic SJ. Ketone body modulation of ligand-gated ion channels. Neuropharmacology 2018; 148:21-30. [PMID: 30562540 DOI: 10.1016/j.neuropharm.2018.12.013] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Revised: 11/27/2018] [Accepted: 12/10/2018] [Indexed: 01/01/2023]
Abstract
Ketogenesis is a metabolic process wherein ketone bodies are produced from the breakdown of fatty acids. In humans, fatty acid catabolism results in the production of acetyl-CoA which can then be used to synthesize three ketone bodies: acetoacetate, acetone, and β-hydroxybutyrate. Ketogenesis occurs at a higher rate in situations of low blood glucose, such as during fasting, heavy alcohol consumption, and in situations of low insulin, as well as in individuals who follow a 'ketogenic diet' consisting of low carbohydrate and high fat intake. This diet has various therapeutic indications, including reduction of seizure likelihood in epileptic patients and alcohol withdrawal syndrome. However, the mechanisms underlying these therapeutic benefits are still unclear, with studies suggesting various mechanisms such as a shift in energy production in the brain, effects on neurotransmitter production, or effects on various protein targets. Two-electrode voltage clamp electrophysiology in Xenopus laevis oocytes was used to investigate the actions of ketone bodies on three ionotropic receptors: GABAA, glycine, and NMDA receptors. While physiologically-relevant concentrations of acetone have little effect on inhibitory GABA or glycine receptors, β-hydroxybutyrate inhibits the effects of agonists of these receptors at concentrations achieved in vivo. Additionally, both acetone and β-hydroxybutyrate act as inhibitors of glutamate at the excitatory NMDA receptor. Due to the role of hyperexcitability in the pathogenesis of epilepsy and alcohol withdrawal, the inhibitory actions of acetone and β-hydroxybutyrate at NMDA receptors may underlie the therapeutic benefit of a ketogenic diet for these disorders.
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Affiliation(s)
- Natasha C Pflanz
- Department of Neuroscience, Division of Pharmacology and Toxicology, Waggoner Center for Alcohol and Addiction Research, Institutes for Neuroscience and Cell and Molecular Biology, University of Texas at Austin, Austin, TX, 78712, USA
| | - Anna W Daszkowski
- Department of Neuroscience, Division of Pharmacology and Toxicology, Waggoner Center for Alcohol and Addiction Research, Institutes for Neuroscience and Cell and Molecular Biology, University of Texas at Austin, Austin, TX, 78712, USA
| | - Keith A James
- Department of Neuroscience, Division of Pharmacology and Toxicology, Waggoner Center for Alcohol and Addiction Research, Institutes for Neuroscience and Cell and Molecular Biology, University of Texas at Austin, Austin, TX, 78712, USA
| | - S John Mihic
- Department of Neuroscience, Division of Pharmacology and Toxicology, Waggoner Center for Alcohol and Addiction Research, Institutes for Neuroscience and Cell and Molecular Biology, University of Texas at Austin, Austin, TX, 78712, USA.
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Tang B, Devenish SO, Lummis SCR. Identification of Novel Functionally Important Aromatic Residue Interactions in the Extracellular Domain of the Glycine Receptor. Biochemistry 2018; 57:4029-4035. [DOI: 10.1021/acs.biochem.8b00425] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Bijun Tang
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QH, U.K
| | - Steven O. Devenish
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QH, U.K
| | - Sarah C. R. Lummis
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QH, U.K
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Sparling BA, DiMauro EF. Progress in the discovery of small molecule modulators of the Cys-loop superfamily receptors. Bioorg Med Chem Lett 2017; 27:3207-3218. [DOI: 10.1016/j.bmcl.2017.04.073] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2017] [Revised: 04/20/2017] [Accepted: 04/24/2017] [Indexed: 12/11/2022]
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