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Imamura K, Akagi KI, Miyanoiri Y, Tsujimoto H, Hirokawa T, Ashida H, Murakami K, Inoue A, Suno R, Ikegami T, Sekiyama N, Iwata S, Kobayashi T, Tochio H. Interaction modes of human orexin 2 receptor with selective and nonselective antagonists studied by NMR spectroscopy. Structure 2024; 32:352-361.e5. [PMID: 38194963 DOI: 10.1016/j.str.2023.12.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Revised: 08/17/2023] [Accepted: 12/13/2023] [Indexed: 01/11/2024]
Abstract
Orexin neuropeptides have many physiological roles in the sleep-wake cycle, feeding behavior, reward demands, and stress responses by activating cognitive receptors, the orexin receptors (OX1R and OX2R), distributed in the brain. There are only subtle differences between OX1R and OX2R in the orthosteric site, which has hindered the rational development of subtype-selective antagonists. In this study, we utilized solution-state NMR to capture the structural plasticity of OX2R labeled with 13CH3-ε-methionine in complex with antagonists. Mutations in the orthosteric site allosterically affected the intracellular tip of TM6. Ligand exchange experiments with the subtype-selective EMPA and the nonselective suvorexant identified three methionine residues that were substantially perturbed. The NMR spectra suggested that the suvorexant-bound state exhibited more structural plasticity than the EMPA-bound state, which has not been foreseen from the close similarity of their crystal structures, providing insights into dynamic features to be considered in understanding the ligand recognition mode.
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Affiliation(s)
- Kayo Imamura
- Department of Biophysics, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - Ken-Ichi Akagi
- Section of Laboratory Equipment, National Institute of Biomedical Innovation, Health, and Nutrition, Osaka 567-0085, Japan
| | - Yohei Miyanoiri
- Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Hirokazu Tsujimoto
- Department of Cell Biology and Medical Chemistry, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan
| | - Takatsugu Hirokawa
- Division of Biomedical Science, Faculty of Medicine, University of Tsukuba, Tsukuba 305-8575, Japan; Transborder Medical Research Center, University of Tsukuba, Tsukuba 305-8575, Japan
| | - Hideo Ashida
- Department of Biophysics, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - Kaori Murakami
- Department of Biophysics, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - Asuka Inoue
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Miyagi 980-8578, Japan
| | - Ryoji Suno
- Department of Medical Chemistry, Kansai Medical University, Hirakata 573-1010, Japan
| | - Takahisa Ikegami
- Graduate School of Medical Life Science, Yokohama City University, 1-7-29 Suehiro, Yokohama, Kanagawa 230-0045, Japan
| | - Naotaka Sekiyama
- Department of Biophysics, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - So Iwata
- Department of Cell Biology and Medical Chemistry, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan
| | - Takuya Kobayashi
- Department of Medical Chemistry, Kansai Medical University, Hirakata 573-1010, Japan
| | - Hidehito Tochio
- Department of Biophysics, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan.
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Rich K, Rehman S, Jerman J, Wilkinson G. Investigating the potential of GalR2 as a drug target for neuropathic pain. Neuropeptides 2023; 98:102311. [PMID: 36580831 DOI: 10.1016/j.npep.2022.102311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Revised: 12/12/2022] [Accepted: 12/15/2022] [Indexed: 12/23/2022]
Abstract
Neuropathic pain is a chronic and debilitating condition characterised by episodes of hyperalgesia and allodynia. It occurs following nerve damage from disease, inflammation or injury and currently impacts up to 17% of the UK population. Existing therapies lack efficacy and have deleterious side effects that can be severely limiting. Galanin receptor 2 (GalR2) is a G-protein coupled receptor (GPCR) implicated in the control and processing of painful stimuli. Within the nervous system it is expressed in key tissues involved in these actions such as dorsal root ganglia (DRG) and the dorsal horn of the spinal cord. Stimulation of GalR2 is widely reported to have a role in the attenuation of inflammatory and neuropathic pain. Several studies have indicated GalR2 as a possible drug target, highlighting the potential of specific GalR2 agonists to both provide efficacy and to address the side-effect profiles of current pain therapies in clinical use. A strong biological target for drug discovery will be well validated with regards to its role in the relevant disease pathology. Ideally there will be good translational models, sensitive probes, selective and appropriate molecular tools, translational biomarkers, a clearly defined patient population and strong opportunities for commercialisation. Before GalR2 can be considered as a drug target suitable for investment, key questions need to be asked regarding its expression profile, receptor signalling and ligand interactions. This article aims to critically review the available literature and determine the current strength of hypothesis of GalR2 as a target for the treatment of neuropathic pain.
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Affiliation(s)
- Kirsty Rich
- Medicines Discovery Catapult, Alderley Park, Macclesfield SK10 4ZF, UK.
| | - Samrina Rehman
- Medicines Discovery Catapult, Alderley Park, Macclesfield SK10 4ZF, UK; Division of Evolution and Genomic Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester M13 9PL, UK
| | - Jeff Jerman
- LifeArc, Translational Science, SBC Open Innovation Campus, Stevenage SG1 2FX, UK
| | - Graeme Wilkinson
- Medicines Discovery Catapult, Alderley Park, Macclesfield SK10 4ZF, UK
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