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Koniuszewski F, Vogel FD, Bampali K, Fabjan J, Seidel T, Scholze P, Schmiedhofer PB, Langer T, Ernst M. Molecular Mingling: Multimodal Predictions of Ligand Promiscuity in Pentameric Ligand-Gated Ion Channels. Front Mol Biosci 2022; 9:860246. [PMID: 35615739 PMCID: PMC9124788 DOI: 10.3389/fmolb.2022.860246] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2022] [Accepted: 03/28/2022] [Indexed: 01/23/2023] Open
Abstract
Background: Human pentameric ligand-gated ion channels (pLGICs) comprise nicotinic acetylcholine receptors (nAChRs), 5-hydroxytryptamine type 3 receptors (5-HT3Rs), zinc-activated channels (ZAC), γ-aminobutyric acid type A receptors (GABAARs) and glycine receptors (GlyRs). They are recognized therapeutic targets of some of the most prescribed drugs like general anesthetics, anxiolytics, smoking cessation aids, antiemetics and many more. Currently, approximately 100 experimental structures of pLGICs with ligands bound exist in the protein data bank (PDB). These atomic-level 3D structures enable the generation of a comprehensive binding site inventory for the superfamily and the in silico prediction of binding site properties. Methods: A panel of high throughput in silico methods including pharmacophore screening, conformation analysis and descriptor calculation was applied to a selection of allosteric binding sites for which in vitro screens are lacking. Variant abundance near binding site forming regions and computational docking complement the approach. Results: The structural data reflects known and novel binding sites, some of which may be unique to individual receptors, while others are broadly conserved. The membrane spanning domain, comprising four highly conserved segments, contains ligand interaction sites for which in vitro assays suitable for high throughput screenings are critically lacking. This is also the case for structurally more variable novel sites in the extracellular domain. Our computational results suggest that the phytocannabinoid Δ9-tetrahydrocannabinol (Δ9-THC) can utilize multiple pockets which are likely to exist on most superfamily members. Conclusion: With this study, we explore the potential for polypharmacology among pLGICs. Our data suggest that ligands can display two forms of promiscuity to an extent greater than what has been realized: 1) Ligands can interact with homologous sites in many members of the superfamily, which bears toxicological relevance. 2) Multiple pockets in distinct localizations of individual receptor subtypes share common ligands, which counteracts efforts to develop selective agents. Moreover, conformational states need to be considered for in silico drug screening, as certain binding sites display considerable flexibility. In total, this work contributes to a better understanding of polypharmacology across pLGICs and provides a basis for improved structure guided in silico drug development and drug derisking.
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Affiliation(s)
- Filip Koniuszewski
- Department of Pathobiology of the Nervous System, Center for Brain Research, Medical University Vienna, Vienna, Austria
| | - Florian D. Vogel
- Department of Pathobiology of the Nervous System, Center for Brain Research, Medical University Vienna, Vienna, Austria
| | - Konstantina Bampali
- Department of Pathobiology of the Nervous System, Center for Brain Research, Medical University Vienna, Vienna, Austria
| | - Jure Fabjan
- Department of Pathobiology of the Nervous System, Center for Brain Research, Medical University Vienna, Vienna, Austria
| | - Thomas Seidel
- Department of Pharmaceutical Sciences, Division of Pharmaceutical Chemistry, University of Vienna, Vienna, Austria
| | - Petra Scholze
- Department of Pathobiology of the Nervous System, Center for Brain Research, Medical University Vienna, Vienna, Austria
| | - Philip B. Schmiedhofer
- Department of Pathobiology of the Nervous System, Center for Brain Research, Medical University Vienna, Vienna, Austria
| | - Thierry Langer
- Department of Pharmaceutical Sciences, Division of Pharmaceutical Chemistry, University of Vienna, Vienna, Austria
| | - Margot Ernst
- Department of Pathobiology of the Nervous System, Center for Brain Research, Medical University Vienna, Vienna, Austria
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2
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Irving H, Turek I, Kettle C, Yaakob N. Tapping into 5-HT 3 Receptors to Modify Metabolic and Immune Responses. Int J Mol Sci 2021; 22:ijms222111910. [PMID: 34769340 PMCID: PMC8584345 DOI: 10.3390/ijms222111910] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 10/28/2021] [Accepted: 10/29/2021] [Indexed: 02/07/2023] Open
Abstract
5-hydroxytryptamine type 3 (5-HT3) receptors are ligand gated ion channels, which clearly distinguish their mode of action from the other G-protein coupled 5-HT or serotonin receptors. 5-HT3 receptors are well established targets for emesis and gastrointestinal mobility and are used as adjunct targets in treating schizophrenia. However, the distribution of these receptors is wider than the nervous system and there is potential that these additional sites can be targeted to modulate inflammatory and/or metabolic conditions. Recent progress in structural biology and pharmacology of 5-HT3 receptors have provided profound insights into mechanisms of their action. These advances, combined with insights into clinical relevance of mutations in genes encoding 5-HT3 subunits and increasing understanding of their implications in patient's predisposition to diseases and response to the treatment, open new avenues for personalized precision medicine. In this review, we recap on the current status of 5-HT3 receptor-based therapies using a biochemical and physiological perspective. We assess the potential for targeting 5-HT3 receptors in conditions involving metabolic or inflammatory disorders based on recent findings, underscoring the challenges and limitations of this approach.
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Affiliation(s)
- Helen Irving
- Department of Pharmacy and Biomedical Sciences, La Trobe Institute for Molecular Science, La Trobe University, Bendigo, VIC 3550, Australia; (I.T.); (C.K.)
- Correspondence:
| | - Ilona Turek
- Department of Pharmacy and Biomedical Sciences, La Trobe Institute for Molecular Science, La Trobe University, Bendigo, VIC 3550, Australia; (I.T.); (C.K.)
| | - Christine Kettle
- Department of Pharmacy and Biomedical Sciences, La Trobe Institute for Molecular Science, La Trobe University, Bendigo, VIC 3550, Australia; (I.T.); (C.K.)
| | - Nor Yaakob
- Drug and Herbal Research Centre, Faculty of Pharmacy, Universiti Kebangsaan Malaysia, Jalan Raja Muda Abdul Aziz, Kuala Lumpur 50300, Malaysia;
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3
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Giniatullin R. 5-hydroxytryptamine in migraine: The puzzling role of ionotropic 5-HT 3 receptor in the context of established therapeutic effect of metabotropic 5-HT 1 subtypes. Br J Pharmacol 2021; 179:400-415. [PMID: 34643938 DOI: 10.1111/bph.15710] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2021] [Revised: 09/27/2021] [Accepted: 09/28/2021] [Indexed: 12/16/2022] Open
Abstract
5-hydroxytryptamine (5-HT; serotonin) is traditionally considered as a key mediator implicated in migraine. Multiple 5-HT receptor subtypes contribute to a variety of region-specific functional effects. The raphé nuclei control nociceptive inputs by releasing 5-HT in the brainstem, whereas dural mast cells provide the humoral source of 5-HT in the meninges. Triptans (5-HT1B/D agonists) and ditans (5-HT1F agonists) are the best established 5-HT anti-migraine agents. However, activation of meningeal afferents via ionotropic 5-HT3 receptors results in long-lasting excitatory drive suggesting a pro-nociceptive role for these receptors in migraine. Nevertheless, clinical data do not clearly support the applicability of currently available 5-HT3 antagonists to migraine treatment. The reasons for this might be the presence of 5-HT3 receptors on inhibitory interneurons dampening the excitatory drive, a lack of 5-HT3 A-E subunit-selective antagonists and gender/age-dependent effects. This review is focusing on the controversial role of 5-HT3 receptors in migraine pathology and related pharmacological perspectives of 5-HT ligands.
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Affiliation(s)
- Rashid Giniatullin
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland.,Laboratory of Neurobiology, Kazan Federal University, Kazan, Russia
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4
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McCorkle ML, Kisor DF, Freiermuth CE, Sprague JE. Systematic review of Pharmacogenomics Knowledgebase evidence for pharmacogenomic links to the dopamine reward pathway for heroin dependence. Pharmacogenomics 2021; 22:849-857. [PMID: 34424051 DOI: 10.2217/pgs-2021-0023] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Genetics play an important role in opioid use disorder (OUD); however, few specific gene variants have been identified. Therefore, there is a need to further understand the pharmacogenomics influences on the pharmacodynamics of opioids. The Pharmacogenomics Knowledgebase (PharmGKB), a database that links genetic variation and drug interaction in the body, was queried to identify polymorphisms associated with heroin dependence in the context of opioid related disorders/OUD. Eight genes with 22 variants were identified as linked to increased risk of heroin dependence, with three genes and variants linked to decreased risk, although the level of evidence was moderate to low. Therefore, continued exploration of biomarker influences on OUD, reward pathways and other contributing circuitries is necessary to understand the true impact of genetics on OUD before integration into clinical guidelines.
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Affiliation(s)
| | - David F Kisor
- Department of Pharmaceutical Sciences & Pharmacogenomics, College of Pharmacy, Natural & Health Sciences, Manchester University, Fort Wayne, IN 46845, USA
| | - Caroline E Freiermuth
- Department of Emergency Medicine, University of Cincinnati, Cincinnati, OH 45267, USA.,Center for Addiction Research, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
| | - Jon E Sprague
- The Ohio Attorney General's Office, Columbus, OH 43215, USA.,The Ohio Attorney General's Center for the Future of Forensic Science, Bowling Green State University, Bowling Green, OH 43403, USA
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5
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Gibbs E, Chakrapani S. Structure, Function and Physiology of 5-Hydroxytryptamine Receptors Subtype 3. Subcell Biochem 2021; 96:373-408. [PMID: 33252737 DOI: 10.1007/978-3-030-58971-4_11] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
5-hydroxytryptamine receptor subtype 3 (5-HT3R) is a pentameric ligand-gated ion channel (pLGIC) involved in neuronal signaling. It is best known for its prominent role in gut-CNS signaling though there is growing interest in its other functions, particularly in modulating non-serotonergic synaptic activity. Recent advances in structural biology have provided mechanistic understanding of 5-HT3R function and present new opportunities for the field. This chapter gives a broad overview of 5-HT3R from a physiological and structural perspective and then discusses the specific details of ion permeation, ligand binding and allosteric coupling between these two events. Biochemical evidence is summarized and placed within a physiological context. This perspective underscores the progress that has been made as well as outstanding challenges and opportunities for future 5-HT3R research.
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Affiliation(s)
- Eric Gibbs
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH, 44106-4970, USA.
| | - Sudha Chakrapani
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH, 44106-4970, USA. .,Department of Neuroscience, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106-4970, USA.
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6
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Costescu M, Paunescu H, Coman OA, Coman L, Fulga I. Antidepressant effect of the interaction of fluoxetine with granisetron. Exp Ther Med 2019; 18:5108-5111. [PMID: 31819774 DOI: 10.3892/etm.2019.8141] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Accepted: 10/02/2019] [Indexed: 01/07/2023] Open
Abstract
Selective serotonin reuptake inhibitors (SSRIs) may produce digestive side effects such as nausea and vomiting, diarrhoea and decreased appetite. These side effects are determined by the increase in serotonin availability at 5-HT3 receptors. Granisetron, a serotonin 5-HT3 receptor antagonist, is expected to antagonize the digestive adverse effects of serotonin reuptake inhibitors, but the question is to what extent granisetron influences the antidepressant effect of these substances. The aim of this study was to determine the dose of fluoxetine that has an antidepressant effect in the Porsolt test, and the interaction between fluoxetine and granisetron with respect to the antidepressant effect in this test. In experiment 1, fluoxetine was antidepressant only at 20 mg/kg body weight (bw). In experiment 2, granisetron 1 mg/kg bw had a statistically significant antidepressant effect vs. control. Fluoxetine 20 mg/kg bw associated with a small dose of granisetron (0.1 mg/kg bw) produced a significant antidepressant effect vs. control. This shows that low doses of granisetron associated to fluoxetine might produce a significant antidepressant effect, suggesting a potentiation between these two drugs used in sub-effective antidepressant doses. In conclusion, in our experimental conditions, we can assume that granisetron in low doses could be used to combat intestinal transit disorders produced by SSRI antidepressants. These low doses are preferred, because they increase the antidepressant effect of these SSRIs.
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Affiliation(s)
- Mihnea Costescu
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, UMF Carol Davila, 050474 Bucharest, Romania
| | - Horia Paunescu
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, UMF Carol Davila, 050474 Bucharest, Romania
| | - Oana Andreia Coman
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, UMF Carol Davila, 050474 Bucharest, Romania
| | - Laurențiu Coman
- Department of Physiology, Faculty of Pharmacy, UMF Carol Davila, 050474 Bucharest, Romania
| | - Ion Fulga
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, UMF Carol Davila, 050474 Bucharest, Romania
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7
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El-Ayache N, Galligan JJ. 5-HT 3 receptor signaling in serotonin transporter-knockout rats: a female sex-specific animal model of visceral hypersensitivity. Am J Physiol Gastrointest Liver Physiol 2019; 316:G132-G143. [PMID: 30359082 PMCID: PMC6383387 DOI: 10.1152/ajpgi.00131.2018] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The irritable bowel syndrome (IBS) is a functional gastrointestinal motor and visceral sensation disorder that is more common in women than men. Female serotonin transporter (SERT)-gene knockout (KO) rats exhibit hypersensitivity to colorectal balloon distention (CRD) that mimics colonic hypersensitivity occurring in female IBS patients. Alosetron (5-HT3 receptor antagonist) is used to treat diarrhea-predominant IBS in female patients. Other 5-HT3 receptor antagonists are ineffective at treating IBS symptoms. The visceromotor response (VMR) to CRD in SERT-KO and wild-type (WT) rats was measured following subcutaneous (sc), intracerobroventricular (icv), or intrathecal (it) treatment with 5-HT3 receptor antagonists and an agonist. Alosetron (sc) and granisetron (antagonists) caused a paradoxical increase in the VMR to CRD in SERT-KO female rats. Alosetron (sc) increased the VMR to CRD in WT male rats. Alosetron (it) increased the VMR to CRD in SERT-KO female rats only, and the 5-HT3 receptor agonist SR-52772 increased the VMR to CRD in SERT-KO male rats. Depletion of spinal 5-HT using 5,7-dihydroxytryptamine prevented the increase in VMR to CRD in SERT-KO female and male rats treated it with alosetron and SR-52772, respectively. Alosetron (icv) did not affect the VMR to CRD in WT or KO female rats, but it increased the VMR in male SERT-KO but not WT male rats. These data suggest that 5-HT3 receptor signaling at the dorsal spinal cord mediates visceral hypersensitivity in female SERT-KO rats. Such differences could facilitate development of sex-specific drug treatments for visceral pain. NEW & NOTEWORTHY We studied a model of female sex-specific visceral hypersensitivity using rats that had a loss of function of the serotonin transporter (SERT) caused by gene truncation. Female SERT-KO rats exhibited visceral hypersensitivity in response to colorectal balloon distention. We found that increased 5-HT signaling at dorsal spine 5-HT3 receptors was responsible for visceral hypersensitivity in female but not male SERT-KO rats.
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Affiliation(s)
- Nadine El-Ayache
- 1Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan
| | - James J. Galligan
- 1Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan,2Neuroscience Program, Michigan State University, East Lansing, Michigan
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8
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Bhattarai Y, Schmidt BA, Linden DR, Larson ED, Grover M, Beyder A, Farrugia G, Kashyap PC. Human-derived gut microbiota modulates colonic secretion in mice by regulating 5-HT 3 receptor expression via acetate production. Am J Physiol Gastrointest Liver Physiol 2017; 313:G80-G87. [PMID: 28408644 PMCID: PMC5538830 DOI: 10.1152/ajpgi.00448.2016] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/27/2016] [Revised: 03/28/2017] [Accepted: 04/05/2017] [Indexed: 01/31/2023]
Abstract
Serotonin [5-hydroxytryptamine (5-HT)], an important neurotransmitter and a paracrine messenger in the gastrointestinal tract, regulates intestinal secretion by its action primarily on 5-HT3 and 5-HT4 receptors. Recent studies highlight the role of gut microbiota in 5-HT biosynthesis. In this study, we determine whether human-derived gut microbiota affects host secretory response to 5-HT and 5-HT receptor expression. We used proximal colonic mucosa-submucosa preparation from age-matched Swiss Webster germ-free (GF) and humanized (HM; ex-GF colonized with human gut microbiota) mice. 5-HT evoked a significantly greater increase in short-circuit current (ΔIsc) in GF compared with HM mice. Additionally, 5-HT3 receptor mRNA and protein expression was significantly higher in GF compared with HM mice. Ondansetron, a 5-HT3 receptor antagonist, inhibited 5-HT-evoked ΔIsc in GF mice but not in HM mice. Furthermore, a 5-HT3 receptor-selective agonist, 2-methyl-5-hydroxytryptamine hydrochloride, evoked a significantly higher ΔIsc in GF compared with HM mice. Immunohistochemistry in 5-HT3A-green fluorescent protein mice localized 5-HT3 receptor expression to enterochromaffin cells in addition to nerve fibers. The significant difference in 5-HT-evoked ΔIsc between GF and HM mice persisted in the presence of tetrodotoxin (TTX) but was lost after ondansetron application in the presence of TTX. Application of acetate (10 mM) significantly lowered 5-HT3 receptor mRNA in GF mouse colonoids. We conclude that host secretory response to 5-HT may be modulated by gut microbiota regulation of 5-HT3 receptor expression via acetate production. Epithelial 5-HT3 receptor may function as a mediator of gut microbiota-driven change in intestinal secretion.NEW & NOTEWORTHY We found that gut microbiota alters serotonin (5-HT)-evoked intestinal secretion in a 5-HT3 receptor-dependent mechanism and gut microbiota metabolite acetate alters 5-HT3 receptor expression in colonoids.View this article's corresponding video summary at https://www.youtube.com/watch?v=aOMYJMuLTcw&feature=youtu.be.
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Affiliation(s)
- Yogesh Bhattarai
- 1Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota;
| | - Bradley A. Schmidt
- 3Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota
| | - David R. Linden
- 3Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota
| | - Eric D. Larson
- 2Department of Otolaryngology, University of Colorado School of Medicine, Aurora, Colorado; and
| | - Madhusudan Grover
- 1Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota;
| | - Arthur Beyder
- 1Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota;
| | - Gianrico Farrugia
- 1Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota;
| | - Purna C. Kashyap
- 1Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota;
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Yin F, Ji Y, Zhang J, Guo H, Huang X, Lai J, Wei S. Polymorphisms in the 5-hydroxytryptamine receptor 3B gene are associated with heroin dependence in the Chinese Han population. Neurosci Lett 2016; 635:123-129. [PMID: 27773795 DOI: 10.1016/j.neulet.2016.10.033] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2016] [Revised: 10/06/2016] [Accepted: 10/19/2016] [Indexed: 01/08/2023]
Abstract
Previous studies suggested that the 5-hydroxytryptamine receptor 3B (HTR3B) is involved in heroin dependence by modulating dopamine (DA) release in the reward pathway and that the genetic polymorphisms in HTR3B play plausible role in modulating the risk of developing heroin addiction. To identify markers that contribute to the genetic susceptibility to heroin dependence, we examined the potential associations between heroin dependence and 7 single nucleotide polymorphisms (SNPs) of the HTR3B gene using multiplex SNaPshot technology in a Chinese Han population. Participants included 418 heroin-dependent subjects and 422 healthy controls. The results suggested that the genotype distribution of HTR3B rs1176746 and rs1185027 were significantly different between heroin dependent subjects and healthy controls (both p=0.004). The frequency of the GG of rs1176746 and AA of rs1185027 genotype in heroin-dependent subjects were significantly higher than that of healthy controls, while the GA of rs1176746 and AT of rs1185027 genotype distributions were much lower. Another SNP, rs10789970, showed a nominally significant p-value in the genotype distribution between heroin dependent subjects and controls (p=0.022). These findings indicate the important role of HTR3B polymorphisms in heroin dependence among the Chinese Han population and provide valuable information for further genetic and neurobiological investigations of heroin dependence.
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Affiliation(s)
- Fangyuan Yin
- College of Forensic, Key Laboratory of Ministry of Public Health for Forensic Science, Xi'an Jiaotong University, Xi'an, Shaanxi, People's Republic of China
| | - Yuanyuan Ji
- College of Forensic, Key Laboratory of Ministry of Public Health for Forensic Science, Xi'an Jiaotong University, Xi'an, Shaanxi, People's Republic of China
| | - Jing Zhang
- College of Forensic, Key Laboratory of Ministry of Public Health for Forensic Science, Xi'an Jiaotong University, Xi'an, Shaanxi, People's Republic of China
| | - Hao Guo
- College of Forensic, Key Laboratory of Ministry of Public Health for Forensic Science, Xi'an Jiaotong University, Xi'an, Shaanxi, People's Republic of China
| | - Xin Huang
- College of Forensic, Key Laboratory of Ministry of Public Health for Forensic Science, Xi'an Jiaotong University, Xi'an, Shaanxi, People's Republic of China
| | - Jianghua Lai
- College of Forensic, Key Laboratory of Ministry of Public Health for Forensic Science, Xi'an Jiaotong University, Xi'an, Shaanxi, People's Republic of China; Key Laboratory of Environment and Genes Related to Diseases, Ministry of Education, Xi'an Jiaotong University, Xi'an, Shaanxi, People's Republic of China
| | - Shuguang Wei
- College of Forensic, Key Laboratory of Ministry of Public Health for Forensic Science, Xi'an Jiaotong University, Xi'an, Shaanxi, People's Republic of China; Key Laboratory of Environment and Genes Related to Diseases, Ministry of Education, Xi'an Jiaotong University, Xi'an, Shaanxi, People's Republic of China.
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10
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Kim HW, Kang JI, Lee SH, An SK, Sohn SY, Hwang EH, Lee SY, Kim SJ. Common variants of HTR3 genes are associated with obsessive-compulsive disorder and its phenotypic expression. Sci Rep 2016; 6:32564. [PMID: 27616601 PMCID: PMC5018838 DOI: 10.1038/srep32564] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Accepted: 08/09/2016] [Indexed: 12/24/2022] Open
Abstract
Evidence from literature supports the existence of associations between serotonin-related genetic variants and obsessive-compulsive disorder (OCD), but few studies have explored the involvement of serotonin receptor type 3 genes (HTR3) in OCD. To identify whether HTR3 variability affects an individual’s susceptibility to OCD, we examined 10 HTR3 variants in 596 individuals with OCD and 599 controls. A significant difference existed in the genotypic distribution of the HTR3B variant rs1176744 between individuals with OCD and controls (odds ratio [OR] = 0.74, 95% confidence interval [CI] = 0.60–0.91, P = 0.0043). A protective haplotype in HTR3B was also associated with OCD (OR = 0.77, CI = 0.63–0.95, permutated P = 0.0179). Analyses of OCD sub-phenotypes demonstrated significant associations between rs3758987 and early onset OCD in male subjects (OR = 0.49, CI = 0.31–0.79, P = 0.0031) and among rs6766410, rs6443930, and the cleaning dimension in female subjects (OR = 0.36, CI = 0.18–0.69, P = 0.0016 and OR = 0.47, CI = 0.29–0.79, P = 0.0030, respectively). Additionally, rs6766410 was related to contamination-based disgust in OCD (P = 0.0044). These results support that common HTR3 variants are involved in OCD and some of its clinical phenotypes.
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Affiliation(s)
- Hae Won Kim
- Department of Psychiatry, Yonsei University College of Medicine, Seoul, Republic of Korea.,Institute of Behavioral Science in Medicine, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Jee In Kang
- Department of Psychiatry, Yonsei University College of Medicine, Seoul, Republic of Korea.,Institute of Behavioral Science in Medicine, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Sang-Hyuk Lee
- Department of Psychiatry, CHA Bundang Medical Center, CHA University, Seongnam, Republic of Korea
| | - Suk Kyoon An
- Department of Psychiatry, Yonsei University College of Medicine, Seoul, Republic of Korea.,Institute of Behavioral Science in Medicine, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Sung Yun Sohn
- Department of Psychiatry, Yonsei University College of Medicine, Seoul, Republic of Korea.,Institute of Behavioral Science in Medicine, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Eun Hee Hwang
- Institute of Behavioral Science in Medicine, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Su Young Lee
- Department of Psychiatry, Cheil General Hospital &Women's Healthcare Center, Dankook University College of Medicine, Seoul, Republic of Korea
| | - Se Joo Kim
- Department of Psychiatry, Yonsei University College of Medicine, Seoul, Republic of Korea.,Institute of Behavioral Science in Medicine, Yonsei University College of Medicine, Seoul, Republic of Korea
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A New Mechanism of Receptor Targeting by Interaction between Two Classes of Ligand-Gated Ion Channels. J Neurosci 2016; 36:1456-70. [PMID: 26843630 DOI: 10.1523/jneurosci.2390-15.2016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
UNLABELLED The 5-HT3 receptors are serotonin-gated ion channels that physically couple with purinergic P2X2 receptors to trigger a functional cross-inhibition leading to reciprocal channel occlusion. Although this functional receptor-receptor coupling seems to serve a modulatory role on both channels, this might not be its main physiological purpose. Using primary cultures of rat hippocampal neurons as a quantitative model of polarized targeting, we show here a novel function for this interaction. In this model, 5-HT3A receptors did not exhibit by themselves the capability of distal targeting in dendrites and axons but required the presence of P2X2R for their proper subcellular localization. 5-HT3AR distal targeting occurred with a delayed time course and exhibited a neuron phenotype dependency. In the subpopulation of neurons expressing endogenous P2X2R, 5-HT3AR distal neuritic localization correlated with P2X2R expression and could be selectively inhibited by P2X2R RNA interference. Cotransfection of both receptors revealed a specific colocalization, cotrafficking in common surface clusters, and the axonal rerouting of 5-HT3AR. The physical association between the two receptors was dependent on the second intracellular loop of the 5-HT3A subunit, but not on the P2X2R C-terminal tail that triggers the functional cross-inhibition with the 5-HT3AR. Together, these data establish that 5-HT3AR distal targeting in axons and dendrites primarily depends on P2X2R expression. Because several P2XR have now been shown to functionally interact with several other members of the 4-TMD family of receptor channels, we propose to reconsider the real functional role for this receptor family, as trafficking partner proteins dynamically involved in other receptors targeting. SIGNIFICANCE STATEMENT So far, receptor targeting mechanisms were found to involve intracellular partner proteins or supramolecular complexes that couple receptors to cytoskeletal elements and recruit them into cargo vesicles. In this paper, we describe a new trafficking mechanism for the neuronal serotonin 5-HT3A ionotropic channel receptor, in which the role of routing partner is endowed by a functionally interacting purinergic receptor: the P2X2 receptor. This work not only unveils the mechanism by which 5-HT3 receptors can reach their axonal localization required for the control of neurotransmitter release, but also suggests that, in addition to their modulatory role, the family of P2X receptors could have a previously undescribed functional role of trafficking partner proteins dynamically involved in the targeting of other receptors.
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12
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Gasiorek A, Trattnig SM, Ahring PK, Kristiansen U, Frølund B, Frederiksen K, Jensen AA. Delineation of the functional properties and the mechanism of action of TMPPAA, an allosteric agonist and positive allosteric modulator of 5-HT3 receptors. Biochem Pharmacol 2016; 110-111:92-108. [DOI: 10.1016/j.bcp.2016.04.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2016] [Accepted: 04/06/2016] [Indexed: 10/21/2022]
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13
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Activation and modulation of recombinantly expressed serotonin receptor type 3A by terpenes and pungent substances. Biochem Biophys Res Commun 2015; 467:1090-6. [DOI: 10.1016/j.bbrc.2015.09.074] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Accepted: 09/12/2015] [Indexed: 11/22/2022]
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14
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Pytka K, Podkowa K, Rapacz A, Podkowa A, Żmudzka E, Olczyk A, Sapa J, Filipek B. The role of serotonergic, adrenergic and dopaminergic receptors in antidepressant-like effect. Pharmacol Rep 2015; 68:263-74. [PMID: 26922526 DOI: 10.1016/j.pharep.2015.08.007] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Revised: 07/29/2015] [Accepted: 08/12/2015] [Indexed: 01/11/2023]
Abstract
Depression is a serious global illness, becoming more and more common in developed countries. Because of specific symptoms it is considered as a leading cause of disability all over the world with a high death factor due to suicides. There are many antidepressants used in the therapy, but still more than 30% of patients do not respond to the treatment. The heterogeneous nature of the illness and its complex, unclear aetiology may be responsible for these difficulties. Next to the main monoaminergic hypothesis of depression there are also many other approaches connected with the pathophysiology of the disease, including hypothalamic-pituitary-adrenal axis dysregulation, dopaminergic, cholinergic, glutamatergic or GABA-ergic neurotransmission. Nevertheless, it can be unambiguously stated that serotonergic, noradrenergic and dopaminergic systems are precisely connected with pathogenesis of depression, and should be therefore considered as valuable targets in patients' treatment. Bearing that in mind, this review presents the role of serotonergic, adrenergic and dopaminergic receptors in antidepressant-like effect.
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Affiliation(s)
- Karolina Pytka
- Department of Pharmacodynamics, Faculty of Pharmacy, Jagiellonian University Medical College, Kraków, Poland.
| | - Karolina Podkowa
- Department of Neurobiology, Institute of Pharmacology Polish Academy of Sciences, Kraków, Poland
| | - Anna Rapacz
- Department of Pharmacodynamics, Faculty of Pharmacy, Jagiellonian University Medical College, Kraków, Poland
| | - Adrian Podkowa
- Department of Pharmacodynamics, Faculty of Pharmacy, Jagiellonian University Medical College, Kraków, Poland
| | - Elżbieta Żmudzka
- Department of Pharmacodynamics, Faculty of Pharmacy, Jagiellonian University Medical College, Kraków, Poland
| | - Adrian Olczyk
- Institute of Automatic Control, Silesian University of Technology, Gliwice, Poland
| | - Jacek Sapa
- Department of Pharmacodynamics, Faculty of Pharmacy, Jagiellonian University Medical College, Kraków, Poland
| | - Barbara Filipek
- Department of Pharmacodynamics, Faculty of Pharmacy, Jagiellonian University Medical College, Kraków, Poland
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15
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Immunomodulatory effects mediated by serotonin. J Immunol Res 2015; 2015:354957. [PMID: 25961058 PMCID: PMC4417587 DOI: 10.1155/2015/354957] [Citation(s) in RCA: 172] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Accepted: 02/24/2015] [Indexed: 11/17/2022] Open
Abstract
Serotonin (5-HT) induces concentration-dependent metabolic effects in diverse cell types, including neurons, entherochromaffin cells, adipocytes, pancreatic beta-cells, fibroblasts, smooth muscle cells, epithelial cells, and leukocytes. Three classes of genes regulating 5-HT function are constitutively expressed or induced in these cells: (a) membrane proteins that regulate the response to 5-HT, such as SERT, 5HTR-GPCR, and the 5HT3-ion channels; (b) downstream signaling transduction proteins; and (c) enzymes controlling 5-HT metabolism, such as IDO and MAO, which can generate biologically active catabolites, including melatonin, kynurenines, and kynurenamines. This review covers the clinical and experimental mechanisms involved in 5-HT-induced immunomodulation. These mechanisms are cell-specific and depend on the expression of serotonergic components in immune cells. Consequently, 5-HT can modulate several immunological events, such as chemotaxis, leukocyte activation, proliferation, cytokine secretion, anergy, and apoptosis. The effects of 5-HT on immune cells may be relevant in the clinical outcome of pathologies with an inflammatory component. Major depression, fibromyalgia, Alzheimer disease, psoriasis, arthritis, allergies, and asthma are all associated with changes in the serotonergic system associated with leukocytes. Thus, pharmacological regulation of the serotonergic system may modulate immune function and provide therapeutic alternatives for these diseases.
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16
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Miles TF, Lester HA, Dougherty DA. Allosteric activation of the 5-HT3AB receptor by mCPBG. Neuropharmacology 2014; 91:103-8. [PMID: 25541413 DOI: 10.1016/j.neuropharm.2014.12.018] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Revised: 10/16/2014] [Accepted: 12/10/2014] [Indexed: 10/25/2022]
Abstract
The 5-HT3AB receptor contains three A and two B subunits in an A-A-B-A-B order. However, serotonin function at the 5-HT3AB receptor has been shown to depend solely on the A-A interface present in the homomeric receptor. Using mutations at sites on both the primary (E122) and complementary (Y146) faces of the B subunit, we demonstrate that meta-chlorophenyl biguanide (mCPBG), a 5-HT3 selective agonist, is capable of binding to and activating the 5-HT3AB receptor at all five subunit interfaces of the heteromer. Further, mCPBG is capable of allosterically modulating the activity of serotonin from these sites. While these five binding sites are similar enough that they conform to a monophasic dose - response relationship, we uncover subtle differences in the heteromeric binding sites. We also find that the A-A interface appears to contribute disproportionately to the efficacy of 5-HT3AB receptor activation.
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Affiliation(s)
- Timothy F Miles
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E California Blvd, Pasadena, CA 91125, USA
| | - Henry A Lester
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E California Blvd, Pasadena, CA 91125, USA
| | - Dennis A Dougherty
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 E California Blvd, Pasadena, CA 91125, USA.
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17
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Thompson AJ, Lummis SCR. Discriminating between 5-HT₃A and 5-HT₃AB receptors. Br J Pharmacol 2014; 169:736-47. [PMID: 23489111 PMCID: PMC3687655 DOI: 10.1111/bph.12166] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2012] [Revised: 01/07/2013] [Accepted: 02/04/2013] [Indexed: 12/19/2022] Open
Abstract
The 5-HT3B subunit was first cloned in 1999, and co-expression with the 5-HT3A subunit results in heteromeric 5-HT₃AB receptors that are functionally distinct from homomeric 5-HT₃A receptors. The affinities of competitive ligands at the two receptor subtypes are usually similar, but those of non-competitive antagonists that bind in the pore often differ. A competitive ligand and allosteric modulator that distinguishes 5-HT₃A from 5-HT₃AB receptors has recently been described, and the number of non-competitive antagonists identified with this ability has increased in recent years. In this review, we discuss the differences between 5-HT₃A and 5-HT₃AB receptors and describe the possible sites of action of compounds that can distinguish between them.
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Affiliation(s)
- A J Thompson
- Department of Biochemistry, University of Cambridge, Cambridge, UK.
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18
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Alexander SPH, Benson HE, Faccenda E, Pawson AJ, Sharman JL, Spedding M, Peters JA, Harmar AJ. The Concise Guide to PHARMACOLOGY 2013/14: ligand-gated ion channels. Br J Pharmacol 2014; 170:1582-606. [PMID: 24528238 PMCID: PMC3892288 DOI: 10.1111/bph.12446] [Citation(s) in RCA: 113] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The Concise Guide to PHARMACOLOGY 2013/14 provides concise overviews of the key properties of over 2000 human drug targets with their pharmacology, plus links to an open access knowledgebase of drug targets and their ligands (www.guidetopharmacology.org), which provides more detailed views of target and ligand properties. The full contents can be found at http://onlinelibrary.wiley.com/doi/10.1111/bph.12444/full. Ligand-gated ion channels are one of the seven major pharmacological targets into which the Guide is divided, with the others being G protein-coupled receptors, ion channels, catalytic receptors, nuclear hormone receptors, transporters and enzymes. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. A new landscape format has easy to use tables comparing related targets. It is a condensed version of material contemporary to late 2013, which is presented in greater detail and constantly updated on the website www.guidetopharmacology.org, superseding data presented in previous Guides to Receptors and Channels. It is produced in conjunction with NC-IUPHAR and provides the official IUPHAR classification and nomenclature for human drug targets, where appropriate. It consolidates information previously curated and displayed separately in IUPHAR-DB and the Guide to Receptors and Channels, providing a permanent, citable, point-in-time record that will survive database updates.
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Affiliation(s)
- Stephen P H Alexander
- School of Life Sciences, University of Nottingham Medical School, Nottingham, NG7 2UH, UK
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19
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Thompson AJ, Lummis SCR. A single channel mutation alters agonist efficacy at 5-HT3A and 5-HT3AB receptors. Br J Pharmacol 2014; 170:391-402. [PMID: 23822584 PMCID: PMC3834762 DOI: 10.1111/bph.12287] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Revised: 05/27/2013] [Accepted: 06/14/2013] [Indexed: 01/14/2023] Open
Abstract
BACKGROUND AND PURPOSE 5-HT3 receptors are composed of 5-HT3A subunits (homomeric receptors), or combinations of 5-HT3A and other 5-HT3 receptor subunits (heteromeric receptors, the best studied of which are 5-HT3AB receptors). Here we explore the effects of partial agonists at 5-HT3A and 5-HT3AB receptors, and the importance of a channel-lining residue in determining the efficacy of activation. EXPERIMENTAL APPROACH Wild type and mutant 5-HT3A and 5-HT3AB receptors were expressed in Xenopus oocytes and examined using two-electrode voltage-clamp, or expressed in HEK293 cells and examined using [3H]granisetron binding. KEY RESULTS Dopamine, quipazine and VUF10166 were partial agonists at wild type 5-HT3A and 5-HT3AB receptors, with quipazine and VUF10166 causing a long-lived (>20 min) inhibition of subsequent agonist responses. At 5-HT3A receptors, mCPBG was a partial agonist, but was a superagonist at 5-HT3AB receptors, as it produced a response 2.6× greater than that of 5-HT. A T6'S substitution in the 5-HT3A subunit decreased EC50 and increased Rmax of dopamine and quipazine at both homomeric and heteromeric receptors. The greatest changes were seen with VUF10166 at 5-HT3AT6'SB receptors, where it became a full agonist (EC50 = 7 nM) with an EC50 58-fold less than 5-HT (EC50 = 0.4 μM) and no longer caused inhibition of subsequent agonist responses. CONCLUSIONS AND IMPLICATIONS These results indicate that a mutation in the pore lining domain in both 5-HT3A and 5-HT3AB receptors alters the relative efficacy of a series of agonists, changing some (e.g. quipazine) from apparent antagonists to potent and efficacious agonists.
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Affiliation(s)
- A J Thompson
- Department of Biochemistry, University of Cambridge, Cambridge, UK
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20
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Miles TF, Dougherty DA, Lester HA. The 5-HT3AB receptor shows an A3B2 stoichiometry at the plasma membrane. Biophys J 2014; 105:887-98. [PMID: 23972841 DOI: 10.1016/j.bpj.2013.07.015] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Revised: 06/13/2013] [Accepted: 07/11/2013] [Indexed: 11/16/2022] Open
Abstract
The 5-HT3AB receptor is the best-characterized heteropentameric 5-HT3 receptor. Under conditions of heterologous expression, the 5-HT3AB receptor shows a single functionally resolvable population, suggesting the presence of a unique subunit stoichiometry; however, conflicting previous reports have suggested two different possible stoichiometries. Here we isolate plasma membrane sheets containing assembled receptors from individual HEK293T cells. We then determine the stoichiometry of 5-HT3AB receptors on the plasma membrane by fluorescence methods, employing meCFP- and meYFP-labeled A and B subunits. Over a wide range of cDNA transfection ratios, fluorescence intensity ratios are closest to values that correspond to a subunit ratio of A3B2. Förster resonance energy transfer (family FRET) efficiencies provide minor corrections (3-6%) to the subunit ratios and provide independent support for a predominantly A3B2 stoichiometry on the plasma membrane sheets. Twin FRET efficiencies support these data, also suggesting that the two B subunits are nonadjacent in most of the heteropentamers. The high-frequency variant HTR3B p.Y129S (c.386A>C, rs11767445), linked to psychiatric disease, also forms A3B2 receptors on the plasma membrane. The 5-HT3B Y129S, subunit incorporates in a slightly (11-14%) more efficient manner than the common variant. In general, most of the subunits reside within the cell. In contrast to the findings for the plasma membrane, the relative abundances and FRET characteristics of intracellular subunits depend strongly on the transfection ratio. The straightforward and unambiguous combination of plasma membrane-sheet isolation, fluorescence intensity ratios, and FRET is a generally promising procedure for determining stoichiometry of proteins on the plasma membrane.
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Affiliation(s)
- Timothy F Miles
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
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21
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Engel M, Smidt MP, van Hooft JA. The serotonin 5-HT3 receptor: a novel neurodevelopmental target. Front Cell Neurosci 2013; 7:76. [PMID: 23761731 PMCID: PMC3669892 DOI: 10.3389/fncel.2013.00076] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2013] [Accepted: 05/06/2013] [Indexed: 01/28/2023] Open
Abstract
Serotonin (5-hydroxytryptamine, 5-HT), next to being an important neurotransmitter, recently gained attention as a key-regulator of pre- and postnatal development in the mammalian central nervous system (CNS). Several receptors for 5-HT are expressed in the developing brain including a ligand-gated ion channel, the 5-HT3 receptor. Over the past years, evidence has been accumulating that 5-HT3 receptors are involved in the regulation of neurodevelopment by serotonin. Here, we review the spatial and temporal expression patterns of 5-HT3 receptors in the pre- and early postnatal rodent brain and its functional implications. First, 5-HT3 receptors are expressed on GABAergic interneurons in neocortex and limbic structures derived from the caudal ganglionic eminence. Mature inhibitory GABAergic interneurons fine-tune neuronal excitability and thus are crucial for the physiological function of the brain. Second, 5-HT3 receptors are expressed on specific glutamatergic neurons, Cajal-Retzius cells in the cortex and granule cells in the cerebellum, where they regulate morphology, positioning, and connectivity of the local microcircuitry. Taken together, the 5-HT3 receptor emerges as a potential key-regulator of network formation and function in the CNS, which could have a major impact on our understanding of neurodevelopmental disorders in which 5-HT plays a role.
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Affiliation(s)
- Mareen Engel
- Center for NeuroScience, Swammerdam Institute for Life Sciences, University of AmsterdamAmsterdam, Netherlands
- Max Planck Institute of PsychiatryMunich, Germany
| | - Marten P. Smidt
- Center for NeuroScience, Swammerdam Institute for Life Sciences, University of AmsterdamAmsterdam, Netherlands
| | - Johannes A. van Hooft
- Center for NeuroScience, Swammerdam Institute for Life Sciences, University of AmsterdamAmsterdam, Netherlands
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22
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Thompson AJ, Verheij MHP, van Muijlwijk-Koezen JE, Lummis SCR, Leurs R, de Esch IJP. Structure-activity relationships of quinoxaline-based 5-HT3A and 5-HT3AB receptor-selective ligands. ChemMedChem 2013; 8:946-55. [PMID: 23640722 PMCID: PMC4063337 DOI: 10.1002/cmdc.201300032] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2013] [Revised: 03/15/2013] [Indexed: 12/23/2022]
Abstract
Until recently, discriminating between homomeric 5-HT3A and heteromeric 5-HT3AB receptors was only possible with ligands that bind in the receptor pore. This study describes the first series of ligands that can discriminate between these receptor types at the level of the orthosteric binding site. During a recent fragment screen, 2-chloro-3-(4-methylpiperazin-1-yl)quinoxaline (VUF10166) was identified as a ligand that displays an 83-fold difference in [(3)H]granisetron binding affinity between 5-HT3A and 5-HT3AB receptors. Fragment hit exploration, initiated from VUF10166 and 3-(4-methylpiperazin-1-yl)quinoxalin-2-ol, resulted in a series of compounds with higher affinity at either 5-HT3A or 5-HT3AB receptors. These ligands reveal that a single atom is sufficient to change the selectivity profile of a compound. At the extremes of the new compounds were 2-amino-3-(4-methylpiperazin-1-yl)quinoxaline, which showed 11-fold selectivity for the 5-HT3A receptor, and 2-(4-methylpiperazin-1-yl)quinoxaline, which showed an 8.3-fold selectivity for the 5-HT3AB receptor. These compounds represent novel molecular tools for studying 5-HT3 receptor subtypes and could help elucidate their physiological roles.
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23
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Desai R, Miller KW, Raines DE. The pyrrole etomidate analog carboetomidate potently inhibits human 5-HT3A receptor function: comparisons with etomidate and potential implications for emetogenesis. Anesth Analg 2013; 116:573-9. [PMID: 23400978 DOI: 10.1213/ane.0b013e31827d204d] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
BACKGROUND 5-Hydroxytryptamine type 3 (5-HT(3)) receptors are excitatory ion channels belonging to the cys-loop family of ligand-gated ion channels. They are involved in nausea and vomiting and their antagonists are used clinically as antiemetic drugs. We previously reported the development of a novel pyrrole analog of etomidate, (R)-ethyl 1-(1-phenylethyl)-1H-pyrrole-2-carboxylate (carboetomidate), which retains etomidate's desirable anesthetic and hemodynamic properties, but lacks its potent inhibitory effect on adrenocorticotropic hormone-stimulated steroid synthesis. Also in contrast to etomidate, carboetomidate potently inhibits nicotinic acetylcholine receptors. Because nicotinic acetylcholine and 5-HT(3) receptors are highly homologous, we hypothesized that carboetomidate might also potently inhibit 5-HT(3) receptors with potentially important implications for the drug's emetogenic activity. In the current studies, we investigated and compared modulation of 5-HT(3A) receptors by carboetomidate and etomidate. METHODS 5-HT(3) receptors were heterologously expressed in human embryonic kidney cells. Drugs were applied with a multichannel superfusion pipette coupled to piezoelectric elements, and currents were recorded from cells in either the whole-cell or excised outside-out patch configuration of patch-clamp recordings. RESULTS Carboetomidate and etomidate inhibited integrated 5-HT(3A) receptor-mediated currents with respective half-inhibitory concentrations of 1.9 μM (95% confidence interval [CI] = 1.4-2.7 μM) and 25 μM (95% CI = 17-37 μM). These values may be compared with respective hypnotic concentrations of 5.4 and 2.3 µM. This inhibition reflected hypnotic effects on peak current amplitudes and desensitization rates. Half-inhibitory concentrations for reducing peak current amplitudes were 34 μM (95% CI = 24-48 µM) for carboetomidate and 171 μM (95% CI = 128-228 µM) for etomidate. Half-inhibitory concentrations for reducing the desensitization time constant were 3.5 μM (95% CI = 2.4-5.1 µM) for carboetomidate and 36 μM (95% CI = 21-59 µM) for etomidate. CONCLUSIONS In contrast to etomidate, carboetomidate inhibits 5-HT(3A) receptor-mediated currents at hypnotic concentrations. This inhibition is primarily the result of enhancing the rate of desensitization. Because carboetomidate potently inhibits 5-HT(3A) receptors, it may be less emetogenic than etomidate.
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Affiliation(s)
- Rooma Desai
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, 55 Fruit St., Boston, MA 02114-2621, USA
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24
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Jensen AA, Plath N, Pedersen MHF, Isberg V, Krall J, Wellendorph P, Stensbøl TB, Gloriam DE, Krogsgaard-Larsen P, Frølund B. Design, synthesis, and pharmacological characterization of N- and O-substituted 5,6,7,8-tetrahydro-4H-isoxazolo[4,5-d]azepin-3-ol analogues: novel 5-HT(2A)/5-HT(2C) receptor agonists with pro-cognitive properties. J Med Chem 2013; 56:1211-27. [PMID: 23301527 DOI: 10.1021/jm301656h] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The isoxazol-3-one tautomer of the bicyclic isoxazole, 5,6,7,8-tetrahydro-4H-isoxazolo[4,5-d]azepin-3-ol (THAZ), has previously been shown to be a weak GABA(A) and glycine receptor antagonist. In the present study, the potential in this scaffold has been explored through the synthesis and pharmacological characterization of a series of N- and O-substituted THAZ analogues. The analogues N-Bn-THAZ (3d) and O-Bn-THAZ (4d) were found to be potent agonists of the human 5-HT(2A) and 5-HT(2C) receptors. Judging from an elaborate pharmacological profiling at numerous other CNS targets, the 3d analogue appears to be selective for the two receptors. Administration of 3d substantially improved the cognitive performance of mice in a place recognition Y-maze model, an effect fully reversible by coadministration of the selective 5-HT(2C) antagonist SB242084. In conclusion, as novel bioavailable cognitive enhancers that most likely mediate their effects through 5-HT(2A) and/or 5-HT(2C) receptors, the isoxazoles 3d and 4d constitute interesting leads for further medicinal chemistry development.
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Affiliation(s)
- Anders A Jensen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, Copenhagen, Denmark.
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25
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Duffy NH, Lester HA, Dougherty DA. Ondansetron and granisetron binding orientation in the 5-HT(3) receptor determined by unnatural amino acid mutagenesis. ACS Chem Biol 2012; 7:1738-45. [PMID: 22873819 DOI: 10.1021/cb300246j] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The serotonin type 3 receptor (5-HT(3)R) is a ligand-gated ion channel found in the central and peripheral nervous systems. The 5-HT(3)R is a therapeutic target, and the clinically available drugs ondansetron and granisetron inhibit receptor activity. Their inhibitory action is through competitive binding to the native ligand binding site, although the binding orientation of the drugs at the receptor has been a matter of debate. Here we heterologously express mouse 5-HT(3)A receptors in Xenopus oocytes and use unnatural amino acid mutagenesis to establish a cation-π interaction for both ondansetron and granisetron to tryptophan 183 in the ligand binding pocket. This cation-π interaction establishes a binding orientation for both ondansetron and granisetron within the binding pocket.
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Affiliation(s)
- Noah H. Duffy
- Division
of Chemistry and Chemical Engineering and ‡Division of Biology, California Institute of Technology,
Pasadena, California 91125, United States
| | - Henry A. Lester
- Division
of Chemistry and Chemical Engineering and ‡Division of Biology, California Institute of Technology,
Pasadena, California 91125, United States
| | - Dennis A. Dougherty
- Division
of Chemistry and Chemical Engineering and ‡Division of Biology, California Institute of Technology,
Pasadena, California 91125, United States
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26
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Miles TF, Bower KS, Lester HA, Dougherty DA. A coupled array of noncovalent interactions impacts the function of the 5-HT3A serotonin receptor in an agonist-specific way. ACS Chem Neurosci 2012; 3:753-60. [PMID: 23077719 DOI: 10.1021/cn3000586] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Accepted: 07/20/2012] [Indexed: 11/28/2022] Open
Abstract
The serotonin type 3A (5-HT(3)A) receptor is a Cys-loop (pentameric) neurotransmitter-gated ion channel found in the central and peripheral nervous systems and implicated in numerous diseases. In previous studies with the endogenous agonist serotonin, we identified two interactions critical for receptor function: a cation-π interaction with W183 in loop B (TrpB) and a hydrogen bond to E129 in loop A. Here we employ mutant cycle analyses utilizing conventional and unnatural amino acid mutagenesis to demonstrate that a third residue, D124 of loop A, forms two functionally important hydrogen bonds to the backbone of loop B. We also show that these three interactions, the cation-π interaction, the backbone hydrogen bonds, and the E129 hydrogen bond, are tightly coupled to each other, suggesting they function as a single unit. We also identify key functional differences between serotonin and the competitive partial agonist m-chlorophenyl biguanide (mCPBG) at these residues. mCPBG displays no cation-π at TrpB and extreme sensitivity to the positioning of E129, on which it is reliant for initiation of channel gating.
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Affiliation(s)
- Timothy F. Miles
- Division
of Biology and ‡Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California
91125, United States
| | - Kiowa S. Bower
- Division
of Biology and ‡Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California
91125, United States
| | - Henry A. Lester
- Division
of Biology and ‡Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California
91125, United States
| | - Dennis A. Dougherty
- Division
of Biology and ‡Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California
91125, United States
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27
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De Rienzo F, Del Cadia M, Menziani MC. A first step towards the understanding of the 5-HT3 receptor subunit heterogeneity from a computational point of view. Phys Chem Chem Phys 2012; 14:12625-36. [PMID: 22880201 DOI: 10.1039/c2cp41028a] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The functional serotonin type-3 receptor (5-HT(3)-R), which is the target of many neuroactive drugs, is known to be a homopentamer made of five identical subunits A (5-HT(3A)-R) or a binary heteropentamer made of subunits A and B (5-HT(3A/B)-R) with a still debated arrangement and stoichiometry. This complex picture has been recently further complicated by the discovery of additional 5-HT(3)-R subunits, C, D, and E, which, similarly to the B subunit, are apparently able to form functional receptors only if co-expressed with subunit A. Being the binding site for both serotonin and antagonists (i.e. drugs) located at the extracellular interface between two adjacent subunits, the large variability of the 5-HT(3)-R composition becomes a crucial issue, since it can originate many different interfaces providing non-equivalent ligand binding sites and complicating the pharmacological modulation. Here, the different 5-HT(3)-R interfaces are analysed, on the bases of the structural conformations of previously built 3D homology models and of the known subunit sequences, by addressing their physicochemical characterization. The results confirm the presence of an aromatic cluster located in the core of the A-A interface as a key determinant for having an interface both stable and functional. This is used as a discriminant to make hypotheses about the capability of all the other possible interfaces constituted by the known 5-HT(3)-R sequences A, B, C, D, and E to build active receptors.
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Affiliation(s)
- Francesca De Rienzo
- Department of Chemistry, University of Modena and Reggio Emilia, Via G. Campi 183, 41100 Modena, Italy
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Trattnig SM, Harpsøe K, Thygesen SB, Rahr LM, Ahring PK, Balle T, Jensen AA. Discovery of a novel allosteric modulator of 5-HT3 receptors: inhibition and potentiation of Cys-loop receptor signaling through a conserved transmembrane intersubunit site. J Biol Chem 2012; 287:25241-54. [PMID: 22589534 DOI: 10.1074/jbc.m112.360370] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The ligand-gated ion channels in the Cys-loop receptor superfamily mediate the effects of neurotransmitters acetylcholine, serotonin, GABA, and glycine. Cys-loop receptor signaling is susceptible to modulation by ligands acting through numerous allosteric sites. Here we report the discovery of a novel class of negative allosteric modulators of the 5-HT(3) receptors (5-HT(3)Rs). PU02 (6-[(1-naphthylmethyl)thio]-9H-purine) is a potent and selective antagonist displaying IC(50) values of ~1 μM at 5-HT(3)Rs and substantially lower activities at other Cys-loop receptors. In an elaborate mutagenesis study of the 5-HT(3)A receptor guided by a homology model, PU02 is demonstrated to act through a transmembrane intersubunit site situated in the upper three helical turns of TM2 and TM3 in the (+)-subunit and TM1 and TM2 in the (-)-subunit. The Ser(248), Leu(288), Ile(290), Thr(294), and Gly(306) residues are identified as important molecular determinants of PU02 activity with minor contributions from Ser(292) and Val(310), and we propose that the naphthalene group of PU02 docks into the hydrophobic cavity formed by these. Interestingly, specific mutations of Ser(248), Thr(294), and Gly(306) convert PU02 into a complex modulator, potentiating and inhibiting 5-HT-evoked signaling through these mutants at low and high concentrations, respectively. The PU02 binding site in the 5-HT(3)R corresponds to allosteric sites in anionic Cys-loop receptors, which emphasizes the uniform nature of the molecular events underlying signaling through the receptors. Moreover, the dramatic changes in the functional properties of PU02 induced by subtle changes in its binding site bear witness to the delicate structural discrimination between allosteric inhibition and potentiation of Cys-loop receptors.
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Affiliation(s)
- Sarah M Trattnig
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark
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Thompson AJ, Verheij MHP, de Esch IJP, Lummis SCR. VUF10166, a novel compound with differing activities at 5-HT₃A and 5-HT₃AB receptors. J Pharmacol Exp Ther 2012; 341:350-9. [PMID: 22306960 PMCID: PMC3336813 DOI: 10.1124/jpet.111.190769] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2011] [Accepted: 01/09/2012] [Indexed: 01/11/2023] Open
Abstract
The actions of a novel, potent 5-HT₃ receptor ligand, [2-chloro-(4-methylpiperazine-1-yl)quinoxaline (VUF10166)], were examined at heterologously expressed human 5-HT₃A and 5-HT₃AB receptors. VUF10166 displaced [³H]granisetron binding to 5-HT₃A receptors expressed in human embryonic kidney cells with high affinity (K(i) = 0.04 nM) but was less potent at 5-HT₃AB receptors (K(i) = 22 nM). Dissociation of [³H]granisetron in the presence of VUF10166 was best fit with a single time constant (t(1/2) = 53 min) at 5-HT₃A receptors, but with two time constants (t(1/2) = 55 and 2.4 min) at 5-HT₃AB receptors. Electrophysiological studies in oocytes revealed that VUF10166 inhibited 5-HT-induced responses at 5-HT₃A receptors at nanomolar concentrations, but inhibition and recovery were too slow to determine an IC₅₀. At 5-HT₃AB receptors, inhibition and recovery were faster, yielding an IC₅₀ of 40 nM. Cysteine substitutions in the complementary (-), but not the principal (+), face of the 5-HT₃B subunit produced heteromeric receptors in which the actions of VUF10166 resembled those at homomeric receptors. At 5-HT₃A receptors, VUF10166 at higher concentrations also behaved as a partial agonist (EC₅₀ = 5.2 μM; R(max) = 0.24) but did not elicit significant responses at 5-HT₃AB receptors at ≤100 μM. Thus, we propose that VUF10166 binds to the common A+A- site of both receptor types and to a second A+B- modulatory site in the heteromeric receptor. The ability of VUF10166 to distinguish between 5-HT₃A and 5-HT₃AB receptors could help evaluate differences between these receptor types and has potential therapeutic value.
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Affiliation(s)
- A J Thompson
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
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Asano H, Miyamoto A, Nakao M, Wakaki C, Iida T, Funakami Y, Wada T, Ichida S. Differential expression of the 5-HT(3A) and 5-HT(3B) receptor in differentiated NG108-15 cells. Neurochem Res 2012; 37:1738-46. [PMID: 22535474 DOI: 10.1007/s11064-012-0784-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2011] [Revised: 04/05/2012] [Accepted: 04/14/2012] [Indexed: 10/28/2022]
Abstract
Previous work from this laboratory has shown that the serotonin (5-HT) induced response is significantly augmented in differentiated NG108-15 (NG) cells treated with dibutyryl cAMP (Bt(2)cAMP) due to qualitative and quantitative changes in the expression of the 5-HT(3) receptor as demonstrated by specific [(3)H] LY-278584 (a selective 5HT(3) receptor antagonist) binding. In this study, we investigated whether there is any change in the relative expression of the 5-HT(3A) and 5-HT(3B) subunits in NG cells differentiated following Bt(2)cAMP treatment cells. The major findings of this study were that the relative amount of 5-HT(3B) subunit mRNA in Bt(2)cAMP-treated NG cells 5 days following Bt(2)cAMP-treatment was greater than that in the untreated cells. In contrast, the relative expression of the 5-HT(3B) subunit protein in the Bt(2)cAMP-treated NG cells was much less than in the untreated cells, but the relative expression of the 5-HT(3A) subunit in the Bt(2)cAMP-treated NG cells was similar to the untreated cells. Therefore, no relationship between mRNA and protein expression for 5-HT(3A) and 5-HT(3B) subunits in Bt(2)cAMP treated and untreated NG cells were observed. It was also found that fluorescent intensity for the 5-HT(3B) subunit in the cell body of the Bt(2)cAMP treated and untreated NG cells gradually decreased from the day 1-5 after Bt(2)cAMP treatment. However, in specific areas such as the varicosity and nerve endings of the Bt(2)cAMP treated cells, staining intensity for the 5-HT(3B) subunits was stronger than in the untreated cells at the all time points, peaking at day 5 post-treatment. These results suggest that the augmented response induced by 5-HT acting via 5-HT(3) receptors in differentiated NG cells may be due to changes in the relative amount of the 5-HT(3B) subunit, particularly the ratio and distribution of the 5-HT(3A) to (3B) subunits.
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Affiliation(s)
- Hajime Asano
- Division of Biochemistry, Kinki University School of Pharmacy, Kowakae, 3-4-1, Higashiosaka 577-8502, Japan
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Replication of functional serotonin receptor type 3A and B variants in bipolar affective disorder: a European multicenter study. Transl Psychiatry 2012; 2:e103. [PMID: 22832903 PMCID: PMC3337070 DOI: 10.1038/tp.2012.30] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Serotonin type 3 receptors (5-HT(3)) are involved in learning, cognition and emotion, and have been implicated in various psychiatric phenotypes. However, their contribution to the pathomechanism of these disorders remains elusive. Three single nucleotide polymorphisms (SNPs) in the HTR3A and HTR3B genes (rs1062613, rs1176744 and rs3831455) have been associated with bipolar affective disorder (BPAD) in pilot studies, and all of them are of functional relevance. We performed a European multicenter study to confirm previous results and provide further evidence for the relevance of these SNPs to the etiology of neuropsychiatric disorders. This involved analysis of the distribution of the three SNPs among 1804 BPAD cases and 2407 healthy controls. A meta-analysis revealed a pooled odds ratio of 0.881 (P = 0.009, 95% confidence intervals = 0.802-0.968) for the non-synonymous functional SNP HTR3B p.Y129S (rs1176744), thereby confirming previous findings. In line with this, the three genome-wide association study samples BOMA (Bonn-Mannheim)-BPAD, WTCCC (Wellcome Trust Case Control Consortium)-BPAD and GAIN (Genetic Association Information Network)-BPAD, including >3500 patients and 5200 controls in total, showed an overrepresentation of the p.Y129 in patients. Remarkably, the meta-analysis revealed a P-value of 0.048 (OR = 0.934, fixed effect model). We also performed expression analyses to gain further insights into the distribution of HTR3A and HTR3B mRNA in the human brain. HTR3A and HTR3B were detected in all investigated brain tissues with the exception of the cerebellum, and large differences in the A:B subunit ratio were observed. Interestingly, expression of the B subunit was most prominent in the brain stem, amygdalae and frontal cortex, regions of relevance to psychiatric disorders. In conclusion, the present study provides further evidence for the presence of impaired 5-HT(3) receptor function in BPAD.
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Simonin J, Vernekar SKV, Thompson AJ, Hothersall JD, Connolly CN, Lummis SCR, Lochner M. High-affinity fluorescent ligands for the 5-HT(3) receptor. Bioorg Med Chem Lett 2011; 22:1151-5. [PMID: 22189135 PMCID: PMC3277886 DOI: 10.1016/j.bmcl.2011.11.097] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2011] [Revised: 11/22/2011] [Accepted: 11/23/2011] [Indexed: 11/28/2022]
Abstract
The synthesis, photophysical and biological characterization of a small library of fluorescent 5-HT(3) receptor ligands is described. Several of these novel granisetron conjugates have high quantum yields and show high affinity for the human 5-HT(3)AR.
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Affiliation(s)
- Jonathan Simonin
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland
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Enoch MA, Gorodetsky E, Hodgkinson C, Roy A, Goldman D. Functional genetic variants that increase synaptic serotonin and 5-HT3 receptor sensitivity predict alcohol and drug dependence. Mol Psychiatry 2011; 16:1139-46. [PMID: 20838391 PMCID: PMC3003772 DOI: 10.1038/mp.2010.94] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The 5-HT3 receptor is rapidly potentiated by ethanol and mediates fast excitatory serotonin (5-HT) transmission that modulates dopamine release in the reward circuitry. The 5-HT transporter regulates synaptic 5-HT availability. Functional polymorphisms in genes encoding the transporter and receptor may therefore influence addiction vulnerability. In this study, 360 treatment-seeking African American male patients with single and comorbid DSM-IV lifetime diagnoses of alcohol, cocaine and heroin dependence and 187 African American male controls were genotyped for the triallelic 5-HTTLPR functional polymorphism in the 5-HT transporter gene (SLC6A4) and 16 haplotype-tagging single-nucleotide polymorphisms (SNPs) across HTR3B (including the functional rs1176744 Tyr129Ser) and HTR3A, genes encoding 5-HT3 receptors. The HTR3B rs1176744 gain-of-function Ser129 allele predicted alcohol dependence (P=0.002) and low 5-HTTLPR activity predicted cocaine/heroin dependence (P=0.01). Both the HTR3B Ser129 allele (P=0.014, odds ratio (OR)=1.7 (1.1-2.6)) and low 5-HTTLPR activity (P=0.011, OR=2.5 (1.3-4.6)) were more common in men with alcohol+drug dependence compared with controls. Moreover, the HTR3B Ser129 allele and low 5-HTTLPR activity had an additive (but not an interactive) effect on alcohol+drug dependence (OR=6.0 (2.1-16.6)) that accounted for 13% of the variance. One possible explanation of our findings is that increased synaptic 5-HT coupled with increased 5-HT3 receptor responsiveness may result in enhanced dopamine transmission in the reward pathway, a predictor of increased risk for addiction. Our results may have pharmacogenetic implications for 5-HT3 therapeutic antagonists such as ondansetron.
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Affiliation(s)
- Mary-Anne Enoch
- Laboratory of Neurogenetics, National Institute on Alcohol Abuse and Alcoholism, NIH, Bethesda, MD, USA
| | - Elena Gorodetsky
- Mood and Anxiety Program, National Institute of Mental Health, NIH, USA
| | - Colin Hodgkinson
- Laboratory of Neurogenetics, National Institute on Alcohol Abuse and Alcoholism, NIH, Bethesda, MD, USA
| | - Alec Roy
- Psychiatry Service, Department of Veterans Affairs, New Jersey VA Health Care System, East Orange, NJ, USA
| | - David Goldman
- Laboratory of Neurogenetics, National Institute on Alcohol Abuse and Alcoholism, NIH, Bethesda, MD, USA
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Ion channels and schizophrenia: a gene set-based analytic approach to GWAS data for biological hypothesis testing. Hum Genet 2011; 131:373-91. [PMID: 21866342 DOI: 10.1007/s00439-011-1082-x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2011] [Accepted: 08/08/2011] [Indexed: 01/11/2023]
Abstract
Schizophrenia is a complex genetic disorder. Gene set-based analytic (GSA) methods have been widely applied for exploratory analyses of large, high-throughput datasets, but less commonly employed for biological hypothesis testing. Our primary hypothesis is that variation in ion channel genes contribute to the genetic susceptibility to schizophrenia. We applied Exploratory Visual Analysis (EVA), one GSA application, to analyze European-American (EA) and African-American (AA) schizophrenia genome-wide association study datasets for statistical enrichment of ion channel gene sets, comparing GSA results derived under three SNP-to-gene mapping strategies: (1) GENIC; (2) 500-Kb; (3) 2.5-Mb and three complimentary SNP-to-gene statistical reduction methods: (1) minimum p value (pMIN); (2) a novel method, proportion of SNPs per Gene with p values below a pre-defined α-threshold (PROP); and (3) the truncated product method (TPM). In the EA analyses, ion channel gene set(s) were enriched under all mapping and statistical approaches. In the AA analysis, ion channel gene set(s) were significantly enriched under pMIN for all mapping strategies and under PROP for broader mapping strategies. Less extensive enrichment in the AA sample may reflect true ethnic differences in susceptibility, sampling or case ascertainment differences, or higher dimensionality relative to sample size of the AA data. More consistent findings under broader mapping strategies may reflect enhanced power due to increased SNP inclusion, enhanced capture of effects over extended haplotypes or significant contributions from regulatory regions. While extensive pMIN findings may reflect gene size bias, the extent and significance of PROP and TPM findings suggest that common variation at ion channel genes may capture some of the heritability of schizophrenia.
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Jørgensen CG, Frølund B, Kehler J, Jensen AA. Discovery of Benzamide Analogues as a Novel Class of 5-HT3 Receptor Agonists. ChemMedChem 2011; 6:725-36. [DOI: 10.1002/cmdc.201000444] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2010] [Revised: 11/24/2010] [Indexed: 11/10/2022]
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Abstract
Cys-loop receptors are membrane-spanning neurotransmitter-gated ion channels that are responsible for fast excitatory and inhibitory transmission in the peripheral and central nervous systems. The best studied members of the Cys-loop family are nACh, 5-HT3, GABAA and glycine receptors. All these receptors share a common structure of five subunits, pseudo-symmetrically arranged to form a rosette with a central ion-conducting pore. Some are cation selective (e.g. nACh and 5-HT3) and some are anion selective (e.g. GABAA and glycine). Each receptor has an extracellular domain (ECD) that contains the ligand-binding sites, a transmembrane domain (TMD) that allows ions to pass across the membrane, and an intracellular domain (ICD) that plays a role in channel conductance and receptor modulation. Cys-loop receptors are the targets for many currently used clinically relevant drugs (e.g. benzodiazepines and anaesthetics). Understanding the molecular mechanisms of these receptors could therefore provide the catalyst for further development in this field, as well as promoting the development of experimental techniques for other areas of neuroscience.In this review, we present our current understanding of Cys-loop receptor structure and function. The ECD has been extensively studied. Research in this area has been stimulated in recent years by the publication of high-resolution structures of nACh receptors and related proteins, which have permitted the creation of many Cys loop receptor homology models of this region. Here, using the 5-HT3 receptor as a typical member of the family, we describe how homology modelling and ligand docking can provide useful but not definitive information about ligand interactions. We briefly consider some of the many Cys-loop receptors modulators. We discuss the current understanding of the structure of the TMD, and how this links to the ECD to allow channel gating, and consider the roles of the ICD, whose structure is poorly understood. We also describe some of the current methods that are beginning to reveal the differences between different receptor states, and may ultimately show structural details of transitions between them.
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Nyce HL, Stober ST, Abrams CF, White MM. Mapping spatial relationships between residues in the ligand-binding domain of the 5-HT3 receptor using a molecular ruler. Biophys J 2010; 98:1847-55. [PMID: 20441748 DOI: 10.1016/j.bpj.2010.01.034] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2009] [Revised: 01/11/2010] [Accepted: 01/14/2010] [Indexed: 12/24/2022] Open
Abstract
The serotonin 5-HT(3) receptor (5-HT(3)R) is a member of the Cys-loop ligand-gated ion channel family. We used a combination of site-directed mutagenesis, homology modeling, and ligand-docking simulations to analyze antagonist-receptor interactions. Mutation of E236, which is near loop C of the binding site, to aspartate prevents expression of the receptor on the cell surface, and no specific ligand binding can be detected. On the other hand, mutation to glutamine, asparagine, or alanine produces receptors that are expressed on the cell surface, but decreases receptor affinity for the competitive antagonist d-tubocurarine (dTC) 5-35-fold. The results of a double-mutant cycle analysis employing a panel of dTC analogs to identify specific points of interactions between the dTC analogs and E236 are consistent with E236 making a direct physical interaction with the 12 -OH of dTC. dTC is a rigid molecule of known three-dimensional structure. Together with previous studies linking other regions of dTC to specific residues in the binding site, these data allow us to define the relative spatial arrangement of three different residues in the ligand-binding site: R92 (loop D), N128 (loop A), and E236 (near loop C). Molecular modeling employing these distance constraints followed by molecular-dynamics simulations produced a dTC/receptor complex consistent with the experimental data. The use of the rigid ligands as molecular rulers in conjunction with double-mutant cycle analysis provides a means of mapping the relative positions of various residues in the ligand-binding site of any ligand-receptor complex, and thus is a useful tool for delineating the architecture of the binding site.
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Affiliation(s)
- Heather L Nyce
- Department of Biochemistry, Drexel University College of Medicine, Philadelphia, Pennsylvania, USA
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Walstab J, Rappold G, Niesler B. 5-HT(3) receptors: role in disease and target of drugs. Pharmacol Ther 2010; 128:146-69. [PMID: 20621123 DOI: 10.1016/j.pharmthera.2010.07.001] [Citation(s) in RCA: 151] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2010] [Accepted: 06/21/2010] [Indexed: 12/19/2022]
Abstract
Serotonin type 3 (5-HT(3)) receptors are pentameric ion channels belonging to the superfamily of Cys-loop receptors. Receptor activation either leads to fast excitatory responses or modulation of neurotransmitter release depending on their neuronal localisation. 5-HT(3) receptors are known to be expressed in the central nervous system in regions involved in the vomiting reflex, processing of pain, the reward system, cognition and anxiety control. In the periphery they are present on a variety of neurons and immune cells. 5-HT(3) receptors are known to be involved in emesis, pain disorders, drug addiction, psychiatric and GI disorders. Progress in molecular genetics gives direction to personalised medical strategies for treating complex diseases such as psychiatric and functional GI disorders and unravelling individual drug responses in pharmacogenetic approaches. Here we discuss the molecular basis of 5-HT(3) receptor diversity at the DNA and protein level, of which our knowledge has greatly extended in the last decade. We also evaluate their role in health and disease and describe specific case-control studies addressing the involvement of polymorphisms of 5-HT3 subunit genes in complex disorders and responses to drugs. Furthermore, we focus on the actual state of the pharmacological knowledge concerning not only classical 5-HT(3) antagonists--the setrons--but also compounds of various substance classes targeting 5-HT(3) receptors such as anaesthetics, opioids, cannabinoids, steroids, antidepressants and antipsychotics as well as natural compounds derived from plants. This shall point to alternative treatment options modulating the 5-HT(3) receptor system and open new possibilities for drug development in the future.
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Affiliation(s)
- Jutta Walstab
- Department of Human Molecular Genetics, University of Heidelberg, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany
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Rajkumar R, Mahesh R. The auspicious role of the 5-HT3 receptor in depression: a probable neuronal target? J Psychopharmacol 2010; 24:455-69. [PMID: 20123937 DOI: 10.1177/0269881109348161] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The serotonergic mechanisms have been successfully utilized by the majority of antidepressant drug discovery programmes, while the search for newer targets remains persistent. The present review focused on the serotonin type-3 receptor, the only ion channel subtype in the serotonin family. Behavioural, neurochemical, electrophysiological and molecular analyses, including the results from our laboratory, provided substantial evidence that rationalizes the correlation between serotonin type-3 receptor modulation and rodent depressive-like behaviour. Nevertheless, the reports on polymorphism of serotonin type-3 receptor genes and data from clinical studies (on serotonin type-3 receptor antagonists) were insufficient to corroborate the involvement of this receptor in the neurobiology of depression. The preclinical and clinical studies that have contradicted the antidepressant-like effects of serotonin type-3 receptor antagonists and the reasons underlying such disagreement were discussed. Finally, this critical review commended the serotonin type-3 receptor as a candidate neuronal antidepressant drug target.
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Feinberg-Zadek PL, Davies PA. Ethanol stabilizes the open state of single 5-hydroxytryptamine(3A)(QDA) receptors. J Pharmacol Exp Ther 2010; 333:896-902. [PMID: 20200118 DOI: 10.1124/jpet.109.164863] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Ethanol enhancement of 5-hydroxytryptamine (5-HT)(3A) receptor-mediated responses may have important consequences in the intoxicating and addictive properties of ethanol. Although the exact mechanism is unknown, ethanol-mediated enhancement of 5-HT(3) receptor current has been proposed to occur due to stabilization of the open-channel state. It has not been possible to directly measure the open state of the channel due to the extremely low single-channel conductance of 5-HT(3A) channels. Recently, three arginine residues within the large intracellular loop of the 5-HT(3A) subunit were substituted by their equivalent residues (glutamine, aspartate, and alanine) of the 5-HT(3B) subunit to produce a 5-HT(3A)(QDA) subunit that forms functional homomeric channels exhibiting a measurable single-channel conductance. Using whole-cell rapid-agonist application techniques and the cell-attached single-channel recording configuration, we examined human 5-HT(3A)(QDA) receptors expressed in human embryonic kidney 293 cells. The agonist sensitivity, macroscopic kinetics, and modulation by ethanol were similar between mutant and wild-type channels, suggesting the substitutions had not altered these channel structure-function properties. The open time histogram for single-channel events mediated by 5-HT(3A)(QDA) receptors in the presence of maximal 5-HT was best fit by three exponentials, but in the presence of ethanol a fourth open state was evident. In summary, the QDA substitution greatly enhanced single-channel conductance with little effect on 5-HT(3A) channel's kinetic properties and ethanol enhances agonist action on 5-HT(3A) receptors by inducing a new, long-lived open-channel state. Furthermore, the 5-HT(3A)(QDA) receptor appears to be suitable for pharmacological studies of 5-HT(3A) receptor modulation at a single-channel level.
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Affiliation(s)
- Paula L Feinberg-Zadek
- Department of Anesthesia and Critical Care, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
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41
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Classification and Signaling Characteristics of 5-HT Receptors. HANDBOOK OF BEHAVIORAL NEUROSCIENCE 2010. [DOI: 10.1016/s1569-7339(10)70073-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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Bartos M, Corradi J, Bouzat C. Structural basis of activation of cys-loop receptors: the extracellular-transmembrane interface as a coupling region. Mol Neurobiol 2009; 40:236-52. [PMID: 19859835 DOI: 10.1007/s12035-009-8084-x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2009] [Accepted: 09/22/2009] [Indexed: 10/25/2022]
Abstract
Cys-loop receptors mediate rapid transmission throughout the nervous system by converting a chemical signal into an electric one. They are pentameric proteins with an extracellular domain that carries the transmitter binding sites and a transmembrane region that forms the ion pore. Their essential function is to couple the binding of the agonist at the extracellular domain to the opening of the ion pore. How the structural changes elicited by agonist binding are propagated through a distance of 50 A to the gate is therefore central for the understanding of the receptor function. A step forward toward the identification of the structures involved in gating has been given by the recently elucidated high-resolution structures of Cys-loop receptors and related proteins. The extracellular-transmembrane interface has attracted attention because it is a structural transition zone where beta-sheets from the extracellular domain merge with alpha-helices from the transmembrane domain. Within this zone, several regions form a network that relays structural changes from the binding site toward the pore, and therefore, this interface controls the beginning and duration of a synaptic response. In this review, the most recent findings on residues and pairwise interactions underlying channel gating are discussed, the main focus being on the extracellular-transmembrane interface.
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Affiliation(s)
- Mariana Bartos
- Instituto de Investigaciones Bioquímicas, UNS-CONICET, Bahía Blanca, Argentina
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Dopico AM, Lovinger DM. Acute alcohol action and desensitization of ligand-gated ion channels. Pharmacol Rev 2009; 61:98-114. [PMID: 19270242 DOI: 10.1124/pr.108.000430] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Ethanol exerts its biological actions through multiple receptors, including ion channels. Ion channels that are sensitive to pharmacologically relevant ethanol concentrations constitute a heterogeneous set, including structurally unrelated proteins solely sharing the property that their gating is regulated by a ligand(s). Receptor desensitization is almost universal among these channels, and its modulation by ethanol may be a crucial aspect of alcohol pharmacology and effects in the body. We review the evidence documenting interactions between ethanol and ionotropic receptor desensitization, and the contribution of this interaction to overall ethanol action on channel function. In some cases, such as type 3 serotonin, nicotinic acetylcholine, GABA-A, and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate receptors, ethanol actions on apparent desensitization play a significant role in acute drug action on receptor function. In a few cases, mutagenesis helped to identify different areas within a receptor protein that differentially sense n-alcohols, resulting in differential modulation of receptor desensitization. However, desensitization of a receptor is linked to a variety of biochemical processes that may alter protein conformation, such as the lipid microenvironment, post-translational channel modification, and channel subunit composition, the relative contribution of these processes to ethanol interactions with channel desensitization remains unclear. Understanding interactions between ethanol and ionotropic receptor desensitization may help to explain different ethanol actions 1) when ethanol is evaluated in vitro on cloned channel proteins, 2) under physiological or pathological conditions or in distinct cell domains with modified ligand concentration and/or receptor conformation. Finally, receptor desensitization is likely to participate in molecular and, possibly, behavioral tolerance to ethanol, which is thought to contribute to the risk of alcoholism.
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Affiliation(s)
- Alex M Dopico
- Department of Pharmacology, University of Tennessee Health Science Center, 874 Union Avenue, Memphis, TN 38163-0001, USA.
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Barnes NM, Hales TG, Lummis SC, Peters JA. The 5-HT3 receptor--the relationship between structure and function. Neuropharmacology 2009; 56:273-84. [PMID: 18761359 PMCID: PMC6485434 DOI: 10.1016/j.neuropharm.2008.08.003] [Citation(s) in RCA: 174] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2008] [Revised: 07/31/2008] [Accepted: 08/01/2008] [Indexed: 12/15/2022]
Abstract
The 5-hydroxytryptamine type-3 (5-HT3) receptor is a cation-selective ion channel of the Cys-loop superfamily. 5-HT3 receptor activation in the central and peripheral nervous systems evokes neuronal excitation and neurotransmitter release. Here, we review the relationship between the structure and the function of the 5-HT3 receptor. 5-HT3A and 5-HT3B subunits are well established components of 5-HT3 receptors but additional HTR3C, HTR3D and HTR3E genes expand the potential for molecular diversity within the family. Studies upon the relationship between subunit structure and the ionic selectivity and single channel conductances of 5-HT3 receptors have identified a novel domain (the intracellular MA-stretch) that contributes to ion permeation and selectivity. Conventional and unnatural amino acid mutagenesis of the extracellular domain of the receptor has revealed residues, within the principle (A-C) and complementary (D-F) loops, which are crucial to ligand binding. An area requiring much further investigation is the subunit composition of 5-HT3 receptors that are endogenous to neurones, and their regional expression within the central nervous system. We conclude by describing recent studies that have identified numerous HTR3A and HTR3B gene polymorphisms that impact upon 5-HT3 receptor function, or expression, and consider their relevance to (patho)physiology.
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Affiliation(s)
- Nicholas M. Barnes
- Cellular and Molecular Neuropharmacology Research Group, Department of Pharmacology, Division of Neuroscience, The Medical School, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Tim G. Hales
- Department of Pharmacology and Physiology, The George Washington University, Washington, DC 20037, USA
| | - Sarah C.R. Lummis
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QW, UK
| | - John A. Peters
- Neurosciences Institute, Division of Pathology and Neuroscience, Ninewells Hospital and Medical School, The University of Dundee, Dundee DD1 9SY, UK
- Corresponding author. Tel.: +44 01382 660111x33117; fax: +44 01382 667120. E-mail address: (J.A. Peters)
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Characterization of the effects of four HTR3B polymorphisms on human 5-HT3AB receptor expression and signalling. Pharmacogenet Genomics 2008; 18:1027-40. [DOI: 10.1097/fpc.0b013e328310f950] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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