1
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Phylogenetic analyses of 5-hydroxytryptamine 3 (5-HT3) receptors in Metazoa. PLoS One 2023; 18:e0281507. [PMID: 36857360 PMCID: PMC9977066 DOI: 10.1371/journal.pone.0281507] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Accepted: 01/24/2023] [Indexed: 03/02/2023] Open
Abstract
The 5-hydroxytrptamine 3 (5-HT3) receptor is a member of the 'Cys-loop' family and the only pentameric ligand gated ion channel among the serotonin receptors. 5-HT3 receptors play an important role in controlling growth, development, and behaviour in animals. Several 5-HT3 receptor antagonists are used to treat diseases (e.g., irritable bowel syndrome, nausea and emesis). Humans express five different subunits (A-E) enabling a variety of heteromeric receptors to form but all contain 5HT3A subunits. However, the information available about the 5-HT3 receptor subunit occurrence among the metazoan lineages is minimal. In the present article we searched for 5-HT3 receptor subunit homologs from different phyla in Metazoa. We identified more than 1000 5-HT3 receptor subunits in Metazoa in different phyla and undertook simultaneous phylogenetic analysis of 526 5HT3A, 358 5HT3B, 239 5HT3C, 70 5HT3D, and 173 5HT3E sequences. 5-HT3 receptor subunits were present in species belonging to 11 phyla: Annelida, Arthropoda, Chordata, Cnidaria, Echinodermata, Mollusca, Nematoda, Orthonectida, Platyhelminthes, Rotifera and Tardigrada. All subunits were most often identified in Chordata phylum which was strongly represented in searches. Using multiple sequence alignment, we investigated variations in the ligand binding region of the 5HT3A subunit protein sequences in the metazoan lineage. Several critical amino acid residues important for ligand binding (common structural features) are commonly present in species from Nematoda and Platyhelminth gut parasites through to Chordata. Collectively, this better understanding of the 5-HT3 receptor evolutionary patterns raises possibilities of future pharmacological challenges facing Metazoa including effects on parasitic and other species in ecosystems that contain 5-HT3 receptor ligands.
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2
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Basak S, Gicheru Y, Kapoor A, Mayer ML, Filizola M, Chakrapani S. Molecular mechanism of setron-mediated inhibition of full-length 5-HT 3A receptor. Nat Commun 2019; 10:3225. [PMID: 31324772 PMCID: PMC6642186 DOI: 10.1038/s41467-019-11142-8] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Accepted: 06/23/2019] [Indexed: 12/27/2022] Open
Abstract
Serotonin receptor (5-HT3AR) is the most common therapeutic target to manage the nausea and vomiting during cancer therapies and in the treatment of irritable bowel syndrome. Setrons, a class of competitive antagonists, cause functional inhibition of 5-HT3AR in the gastrointestinal tract and brainstem, acting as effective anti-emetic agents. Despite their prevalent use, the molecular mechanisms underlying setron binding and inhibition of 5-HT3AR are not fully understood. Here, we present the structure of granisetron-bound full-length 5-HT3AR solved by single-particle cryo-electron microscopy to 2.92 Å resolution. The reconstruction reveals the orientation of granisetron in the orthosteric site with unambiguous density for interacting sidechains. Molecular dynamics simulations and electrophysiology confirm the granisetron binding orientation and the residues central for ligand recognition. Comparison of granisetron-bound 5-HT3AR with the apo and serotonin-bound structures, reveals key insights into the mechanism underlying 5-HT3AR inhibition.
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Affiliation(s)
- Sandip Basak
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH, 44106-4970, USA
| | - Yvonne Gicheru
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH, 44106-4970, USA
| | - Abhijeet Kapoor
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Megan L Mayer
- Division of CryoEM and Bioimaging, SSRL, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, CA, 94025, USA
| | - Marta Filizola
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, 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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3
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Jack T, Leuenberger M, Ruepp MD, Vernekar SKV, Thompson AJ, Braga-Lagache S, Heller M, Lochner M. Mapping the Orthosteric Binding Site of the Human 5-HT 3 Receptor Using Photo-cross-linking Antagonists. ACS Chem Neurosci 2019; 10:438-450. [PMID: 30149702 DOI: 10.1021/acschemneuro.8b00327] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The serotonin-gated 5-HT3 receptor is a ligand-gated ion channel. Its location at the synapse in the central and peripheral nervous system has rendered it a prime pharmacological target, for example, for antiemetic drugs that bind with high affinity to the neurotransmitter binding site and prevent the opening of the channel. Advances in structural biology techniques have led to a surge of disclosed three-dimensional receptor structures; however, solving ligand-bound high-resolution 5-HT3 receptor structures has not been achieved to date. Ligand binding poses in the orthosteric binding site have been largely predicted from mutagenesis and docking studies. We report the synthesis of a series of photo-cross-linking compounds whose structures are based on the clinically used antiemetic drug granisetron (Kytril). These displaced [3H]granisetron from the orthosteric binding site with low nanomolar affinities and showed specific photo-cross-linking with the human 5-HT3 receptor. Detailed analysis by protein-MS/MS identified a residue (Met-228) near the tip of binding loop C as the covalent modification site.
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Affiliation(s)
- Thomas Jack
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland
| | - Michele Leuenberger
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bühlstrasse 28, 3012 Bern, Switzerland
| | - Marc-David Ruepp
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland
| | | | - Andrew J. Thompson
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, U.K
| | - Sophie Braga-Lagache
- Department of BioMedical Research, Mass Spectrometry and Proteomics Laboratory, University of Bern, Inselspital, 3010 Bern, Switzerland
| | - Manfred Heller
- Department of BioMedical Research, Mass Spectrometry and Proteomics Laboratory, University of Bern, Inselspital, 3010 Bern, Switzerland
| | - Martin Lochner
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bühlstrasse 28, 3012 Bern, Switzerland
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4
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Ladefoged LK, Munro L, Pedersen AJ, Lummis SCR, Bang-Andersen B, Balle T, Schiøtt B, Kristensen AS. Modeling and Mutational Analysis of the Binding Mode for the Multimodal Antidepressant Drug Vortioxetine to the Human 5-HT3A Receptor. Mol Pharmacol 2018; 94:1421-1434. [DOI: 10.1124/mol.118.113530] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Accepted: 09/19/2018] [Indexed: 12/23/2022] Open
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5
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Cioffi CL. Modulation of Glycine-Mediated Spinal Neurotransmission for the Treatment of Chronic Pain. J Med Chem 2017; 61:2652-2679. [PMID: 28876062 DOI: 10.1021/acs.jmedchem.7b00956] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Chronic pain constitutes a significant and expanding worldwide health crisis. Currently available analgesics poorly serve individuals suffering from chronic pain, and new therapeutic agents that are more effective, safer, and devoid of abuse liabilities are desperately needed. Among the myriad of cellular and molecular processes contributing to chronic pain, spinal disinhibition of pain signaling to higher cortical centers plays a critical role. Accumulating evidence shows that glycinergic inhibitory neurotransmission in the spinal cord dorsal horn gates nociceptive signaling, is essential in maintaining physiological pain sensitivity, and is diminished in pathological pain states. Thus, it is hypothesized that agents capable of enhancing glycinergic tone within the dorsal horn could obtund nociceptor signaling to the brain and serve as analgesics for persistent pain. This Perspective highlights the potential that pharmacotherapies capable of increasing inhibitory spinal glycinergic neurotransmission hold in providing new and transformative analgesic therapies for the treatment of chronic pain.
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Affiliation(s)
- Christopher L Cioffi
- Departments of Basic and Clinical Sciences and Pharmaceutical Sciences , Albany College of Pharmacy and Health Sciences , 106 New Scotland Avenue , Albany , New York 12208 United States
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6
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Ruepp MD, Wei H, Leuenberger M, Lochner M, Thompson AJ. The binding orientations of structurally-related ligands can differ; A cautionary note. Neuropharmacology 2017; 119:48-61. [PMID: 28137449 PMCID: PMC5464333 DOI: 10.1016/j.neuropharm.2017.01.023] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Revised: 01/13/2017] [Accepted: 01/24/2017] [Indexed: 11/19/2022]
Abstract
Crystal structures can identify ligand-receptor interactions and assist the development of novel therapeutics, but experimental challenges sometimes necessitate the use of homologous proteins. Tropisetron is an orthosteric ligand at both 5-HT3 and α7 nACh receptors and its binding orientation has been determined in the structural homologue AChBP (pdbid: 2WNC). Co-crystallisation with a structurally-related ligand, granisetron, reveals an almost identical orientation (pdbid; 2YME). However, there is a >1000-fold difference in the affinity of tropisetron at 5-HT3 versus α7 nACh receptors, and α7 nACh receptors do not bind granisetron. These striking pharmacological differences prompt questions about which receptor the crystal structures most closely represent and whether the ligand orientations are correct. Here we probe the binding orientation of tropisetron and granisetron at 5-HT3 receptors by in silico modelling and docking, radioligand binding on cysteine-substituted 5-HT3 receptor mutants transiently expressed in HEK 293 cells, and synthetic modification of the ligands. For 15 of the 23 cysteine substitutions, the effects on tropisetron and granisetron were different. Structure-activity relationships on synthesised derivatives of both ligands were also consistent with different orientations, revealing that contrary to the crystallographic evidence from AChBP, the two ligands adopt different orientations in the 5-HT3 receptor binding site. Our results show that even quite structurally similar molecules can adopt different orientations in the same binding site, and that caution may be needed when using homologous proteins to predict ligand binding. The drugs granisetron and tropisetron are structurally similar. Crystals of them bound to AChBP suggest they have similar binding orientations. At 5-HT3R, the effects of mutagenesis indicate that their orientations differ. SAR on both of these drugs also supports different orientations.
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Affiliation(s)
- Marc-David Ruepp
- Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland
| | - Hao Wei
- Department of Pharmacology, University of Cambridge, Cambridge, UK
| | - Michele Leuenberger
- Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland
| | - Martin Lochner
- Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland; Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland.
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Alix K, Khatri S, Mosier PD, Casterlow S, Yan D, Nyce HL, White MM, Schulte MK, Dukat M. Superagonist, Full Agonist, Partial Agonist, and Antagonist Actions of Arylguanidines at 5-Hydroxytryptamine-3 (5-HT 3) Subunit A Receptors. ACS Chem Neurosci 2016; 7:1565-1574. [PMID: 27533595 DOI: 10.1021/acschemneuro.6b00196] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Introduction of minor variations to the substitution pattern of arylguanidine 5-hydroxytryptamine-3 (5-HT3) receptor ligands resulted in a broad spectrum of functionally-active ligands from antagonist to superagonist. For example, (i) introduction of an additional Cl-substituent(s) to our lead full agonist N-(3-chlorophenyl)guanidine (mCPG, 2; efficacy % = 106) yielded superagonists 7-9 (efficacy % = 186, 139, and 129, respectively), (ii) a positional isomer of 2, p-Cl analog 11, displayed partial agonist actions (efficacy % = 12), and (iii) replacing the halogen atom at the meta or para position with an electron donating OCH3 group or a stronger electron withdrawing (i.e., CF3) group resulted in antagonists 13-16. We posit based on combined mutagenesis, crystallographic, and computational analyses that for the 5-HT3 receptor, the arylguanidines that are better able to simultaneously engage the primary and complementary subunits, thus keeping them in close proximity, have greater agonist character while those that are deficient in this ability are antagonists.
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Affiliation(s)
- Katie Alix
- Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, Richmond, Virginia 23298, United States
| | - Shailesh Khatri
- Department
of Pharmaceutical Sciences, Philadelphia College of Pharmacy, University of Sciences, Philadelphia, Pennsylvania 19104, United States
| | - Philip D. Mosier
- Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, Richmond, Virginia 23298, United States
| | - Samantha Casterlow
- Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, Richmond, Virginia 23298, United States
| | - Dong Yan
- Department
of Biochemistry and Molecular Biology Drexel University College of Medicine, Philadelphia, Pennsylvania 19102, United States
| | - Heather L. Nyce
- Department
of Biochemistry and Molecular Biology Drexel University College of Medicine, Philadelphia, Pennsylvania 19102, United States
| | - Michael M. White
- Department
of Biochemistry and Molecular Biology Drexel University College of Medicine, Philadelphia, Pennsylvania 19102, United States
| | - Marvin K. Schulte
- Department
of Pharmaceutical Sciences, Philadelphia College of Pharmacy, University of Sciences, Philadelphia, Pennsylvania 19104, United States
| | - Małgorzata Dukat
- Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, Richmond, Virginia 23298, United States
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8
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Price KL, Lillestol RK, Ulens C, Lummis SCR. Varenicline Interactions at the 5-HT3 Receptor Ligand Binding Site are Revealed by 5-HTBP. ACS Chem Neurosci 2015; 6:1151-7. [PMID: 25648658 PMCID: PMC4505686 DOI: 10.1021/cn500369h] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Cys-loop receptors are the site of action of many therapeutic drugs. One of these is the smoking cessation agent varenicline, which has its major therapeutic effects at nicotinic acetylcholine (nACh) receptors but also acts at 5-HT3 receptors. Here, we report the X-ray crystal structure of the 5-HT binding protein (5-HTBP) in complex with varenicline, and test the predicted interactions by probing the potency of varenicline in a range of mutant 5-HT3 receptors expressed in HEK293 cells and Xenopus oocytes. The structure reveals a range of interactions between varenicline and 5-HTBP. We identified residues within 5 Å of varenicline and substituted the equivalent residues in the 5-HT3 receptor with Ala or a residue with similar chemical properties. Functional characterization of these mutant 5-HT3 receptors, using a fluorescent membrane potential dye in HEK cells and voltage clamp in oocytes, supports interactions between varenicline and the receptor that are similar to those in 5-HTBP. The structure also revealed C-loop closure that was less than in the 5-HT-bound 5-HTBP, and hydrogen bonding between varenicline and the complementary face of the binding pocket via a water molecule, which are characteristics consistent with partial agonist behavior of varenicline in the 5-HT3 receptor. Together, these data reveal detailed insights into the molecular interaction of varenicline in the 5-HT3 receptor.
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Affiliation(s)
- Kerry L Price
- †Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QW, United Kingdom
| | - Reidun K Lillestol
- †Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QW, United Kingdom
| | - Chris Ulens
- ‡The Laboratory of Structural Neurobiology, Department of Cellular and Molecular Medicine, KU Leuven, Herestraat 49, PB 601, B-3000 Leuven, Belgium
| | - Sarah C R Lummis
- †Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QW, United Kingdom
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9
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Matsunaga F, Gao L, Huang XP, Saven JG, Roth BL, Liu R. Molecular interactions between general anesthetics and the 5HT2B receptor. J Biomol Struct Dyn 2013; 33:211-8. [PMID: 24365264 DOI: 10.1080/07391102.2013.869483] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
BACKGROUND Serotonin modulates many processes through a family of seven serotonin receptors. However, no studies have screened for interactions between general anesthetics currently in clinical use and serotonergic G-protein-coupled receptors (GPCRs). Given that both intravenous and inhalational anesthetics have been shown to target other classes of GPCRs, we hypothesized that general anesthetics might interact directly with some serotonin receptors and thus modify their function. METHODS Radioligand binding assays were performed to screen serotonin receptors for interactions with propofol and isoflurane as well as for affinity determinations. Docking calculations using the crystal structure of 5-HT2B were performed to computationally confirm the binding assay results and locate anesthetic binding sites. RESULTS The 5-HT2B class of receptors interacted significantly with both propofol and isoflurane in the primary screen. The affinities for isoflurane and propofol were determined to be 7.78 and .95 μM, respectively, which were at or below the clinical concentrations for both anesthetics. The estimated free energy derived from docking calculations for propofol (-6.70 kcal/mol) and isoflurane (-5.10 kcal/mol) correlated with affinities from the binding assay. The anesthetics were predicted to dock at a pharmacologically relevant binding site of 5HT2B. CONCLUSIONS The molecular interactions between propofol and isoflurane with the 5-HT2B class of receptors were discovered and characterized. This finding implicates the serotonergic GPCRs as potential anesthetic targets.
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Affiliation(s)
- Felipe Matsunaga
- a Department of Anesthesiology and Critical Care , Perelman School of Medicine, University of Pennsylvania , 336 John Morgan Building, 3620 Hamilton Walk, Philadelphia , PA 19104 , USA
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10
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Approaching the 5-HT₃ receptor heterogeneity by computational studies of the transmembrane and intracellular domains. J Comput Aided Mol Des 2013; 27:491-509. [PMID: 23771549 DOI: 10.1007/s10822-013-9658-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Accepted: 06/11/2013] [Indexed: 10/26/2022]
Abstract
5-hydroxytryptamine type-3 receptor (5-HT₃), an important target of many neuroactive drugs, is a cation selective transmembrane pentamer whose functional stoichiometries and subunit arrangements are still debated, due to the extreme complexity of the system. The three dimensional structure of the 5-HT₃R subunits has not been solved so far. Moreover, most of the available structural and functional data is related to the extracellular ligand-binding domain, whereas the transmembrane and the intracellular receptor domains are far less characterised, although they are crucial for receptor function. Here, for the first time, 3D homology models of the transmembrane and the intracellular receptor domains of all the known human 5-HT₃ subunits have been built and assembled into homopentameric (5-HT(3A)R, 5-HT(3B)R, 5-HT(3C)R, 5-HT(3D)R and 5-HT(3E)R) and heteropentameric receptors (5-HT(3AB), 5-HT(3AC), 5-HT(3AD) and 5-HT(3AE)), on the basis of the known three-dimensional structures of the nicotinic-acetylcholine receptor and of the ligand gated channel from Erwinia chrysanthemi. The comparative analyses of sequences, modelled structures, and computed electrostatic properties of the single subunits and of the assembled pentamers shed new light both on the stoichiometric composition and on the physicochemical requirements of the functional receptors. In particular, it emerges that a favourable environment for the crossing of the pore at the transmembrane and intracellular C terminus domain levels by Ca²⁺ ions is granted by the maximum presence of two B subunits in the 5-HT₃ pentamer.
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11
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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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12
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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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13
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Abstract
Inhibitory (or strychnine sensitive) glycine receptors (GlyRs) are anion-selective transmitter-gated ion channels of the cys-loop superfamily, which includes among others also the inhibitory γ-aminobutyric acid receptors (GABA(A) receptors). While GABA mediates fast inhibitory neurotransmission throughout the CNS, the action of glycine as a fast inhibitory neurotransmitter is more restricted. This probably explains why GABA(A) receptors constitute a group of extremely successful drug targets in the treatment of a wide variety of CNS diseases, including anxiety, sleep disorders and epilepsy, while drugs specifically targeting GlyRs are virtually lacking. However, the spatially more restricted distribution of glycinergic inhibition may be advantageous in situations when a more localized enhancement of inhibition is sought. Inhibitory GlyRs are particularly relevant for the control of excitability in the mammalian spinal cord, brain stem and a few selected brain areas, such as the cerebellum and the retina. At these sites, GlyRs regulate important physiological functions, including respiratory rhythms, motor control, muscle tone and sensory as well as pain processing. In the hippocampus, RNA-edited high affinity extrasynaptic GlyRs may contribute to the pathology of temporal lobe epilepsy. Although specific modulators have not yet been identified, GlyRs still possess sites for allosteric modulation by a number of structurally diverse molecules, including alcohols, neurosteroids, cannabinoids, tropeines, general anaesthetics, certain neurotransmitters and cations. This review summarizes the present knowledge about this modulation and the molecular bases of the interactions involved.
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Affiliation(s)
- Gonzalo E Yevenes
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
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14
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Machu TK. Therapeutics of 5-HT3 receptor antagonists: current uses and future directions. Pharmacol Ther 2011; 130:338-47. [PMID: 21356241 PMCID: PMC3103470 DOI: 10.1016/j.pharmthera.2011.02.003] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2011] [Accepted: 02/09/2011] [Indexed: 12/14/2022]
Abstract
The 5-Hydroxytryptamine3 (5-HT3) receptor is a member of the cys-loop family of ligand gated ion channels, of which the nicotinic acetylcholine receptor is the prototype. All other 5-HT receptors identified to date are metabotropic receptors. The 5-HT3 receptor is present in the central and peripheral nervous systems, as well as a number of non-nervous tissues. As an ion channel that is permeable to the cations, Na(+), K(+), and Ca(2+), the 5-HT3 receptor mediates fast depolarizing responses in pre- and post-synaptic neurons. As such, 5-HT3 receptor antagonists that are used clinically block afferent and efferent synaptic transmission. The most well established physiological roles of the 5-HT3 receptor are to coordinate emesis and regulate gastrointestinal motility. Currently marketed 5-HT3 receptor antagonists are indicated for the treatment of chemotherapy, radiation, and anesthesia-induced nausea and vomiting, as well as irritable bowel syndrome. Other therapeutic uses that have been explored include pain and drug addiction. The 5-HT3 receptor is one of a number of receptors that play a role in mediating nausea and vomiting, and as such, 5-HT3 receptor antagonists demonstrate the greatest anti-emetic efficacy when administered in combination with other drug classes.
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Affiliation(s)
- Tina K Machu
- Dept. of Medical Education and Dept. of Pharmacology and Neuroscience, University of North Texas Health Science Center, 3500 Camp Bowie Blvd. Fort Worth, TX 76107-2699, USA.
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15
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Moura Barbosa AJ, De Rienzo F, Ramos MJ, Menziani MC. Computational analysis of ligand recognition sites of homo- and heteropentameric 5-HT3 receptors. Eur J Med Chem 2010; 45:4746-60. [DOI: 10.1016/j.ejmech.2010.07.039] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2010] [Revised: 06/18/2010] [Accepted: 07/20/2010] [Indexed: 11/25/2022]
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16
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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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Agonists and antagonists bind to an A-A interface in the heteromeric 5-HT3AB receptor. Biophys J 2010; 98:1494-502. [PMID: 20409468 DOI: 10.1016/j.bpj.2009.12.4313] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2009] [Revised: 10/22/2009] [Accepted: 12/02/2009] [Indexed: 11/24/2022] Open
Abstract
The 5-HT3 receptor is a member of the Cys-loop family of transmitter receptors. It can function as a homopentamer (5-HT3A-only subunits) or as a heteropentamer. The 5-HT3AB receptor is the best characterized heteropentamer. This receptor differs from a homopentamer in its kinetics, voltage dependence, and single-channel conductance, but its pharmacology is similar. To understand the contribution of the 5-HT3B subunit to the binding site, we created homology models of 5-HT3AB receptors and docked 5-HT and granisetron into AB, BA, and BB interfaces. To test whether ligands bind in any or all of these interfaces, we mutated amino acids that are important for agonist and antagonist binding in the 5-HT3A subunit to their corresponding residues in the 5-HT3B subunit and vice versa. Changes in [3H]granisetron binding affinity (Kd) and 5-HT EC50 were determined using receptors expressed in HEK-293 cells and Xenopus oocytes, respectively. For all A-to-B mutant receptors, except T181N, antagonist binding was altered or eliminated. Functional studies revealed that either the receptors were nonfunctional or the EC50 values were increased. In B-to-A mutant receptors there were no changes in Kd, although EC50 values and Hill slopes, except for N170T mutant receptors, were similar to those for 5-HT3A receptors. Thus, the experimental data do not support a contribution of the 5-HT3B subunit to the binding pocket, and we conclude that both 5-HT and granisetron bind to an AA binding site in the heteromeric 5-HT3AB receptor.
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Vernekar SKV, Hallaq HY, Clarkson G, Thompson AJ, Silvestri L, Lummis SCR, Lochner M. Toward biophysical probes for the 5-HT3 receptor: structure-activity relationship study of granisetron derivatives. J Med Chem 2010; 53:2324-8. [PMID: 20146481 PMCID: PMC4166935 DOI: 10.1021/jm901827x] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
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This report describes the synthesis and biological characterization of novel granisetron derivatives that are antagonists of the human serotonin (5-HT3A) receptor. Some of these substituted granisetron derivatives showed low nanomolar binding affinity and allowed the identification of positions on the granisetron core that might be used as attachment points for biophysical tags. A BODIPY fluorophore was appended to one such position and specifically bound to 5-HT3A receptors in mammalian cells.
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Hazai E, Joshi P, Skoviak EC, Suryanarayanan A, Schulte MK, Bikadi Z. A comprehensive study on the 5-hydroxytryptamine3A receptor binding of agonists serotonin and m-chlorophenylbiguanidine. Bioorg Med Chem 2009; 17:5796-805. [DOI: 10.1016/j.bmc.2009.07.022] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2009] [Revised: 07/06/2009] [Accepted: 07/13/2009] [Indexed: 01/07/2023]
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21
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Maksay G, Laube B, Schemm R, Grudzinska J, Drwal M, Betz H. Different binding modes of tropeines mediating inhibition and potentiation of α1 glycine receptors. J Neurochem 2009; 109:1725-32. [DOI: 10.1111/j.1471-4159.2009.06083.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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22
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Morelli E, Gemma S, Budriesi R, Campiani G, Novellino E, Fattorusso C, Catalanotti B, Coccone SS, Ros S, Borrelli G, Persico M, Fiorini I, Nacci V, Ioan P, Chiarini A, Hamon M, Cagnotto A, Mennini T, Fracasso C, Colovic M, Caccia S, Butini S. Specific Targeting of Peripheral Serotonin 5-HT3 Receptors. Synthesis, Biological Investigation, and Structure−Activity Relationships. J Med Chem 2009; 52:3548-62. [DOI: 10.1021/jm900018b] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Affiliation(s)
- Elena Morelli
- European Research Centre for Drug Discovery and Development, Banchi di Sotto 55, 53100 Siena, Italy, Dipartimento Farmaco Chimico Tecnologico, Università di Siena, Via Aldo Moro 53100 Siena, Italy, Dipartimento di Chimica delle Sostanze Naturali (DCSN) e Dipartimento di Chimica Farmaceutica e Tossicologica (DCFT), Università di Napoli “Federico II”, Via D. Montesano 49, 80131 Napoli, Italy, Dipartimento di Scienze Farmaceutiche, Università di Bologna, Via Belmeloro 6, 40126 Bologna, Italy, Neurobiologie
| | - Sandra Gemma
- European Research Centre for Drug Discovery and Development, Banchi di Sotto 55, 53100 Siena, Italy, Dipartimento Farmaco Chimico Tecnologico, Università di Siena, Via Aldo Moro 53100 Siena, Italy, Dipartimento di Chimica delle Sostanze Naturali (DCSN) e Dipartimento di Chimica Farmaceutica e Tossicologica (DCFT), Università di Napoli “Federico II”, Via D. Montesano 49, 80131 Napoli, Italy, Dipartimento di Scienze Farmaceutiche, Università di Bologna, Via Belmeloro 6, 40126 Bologna, Italy, Neurobiologie
| | - Roberta Budriesi
- European Research Centre for Drug Discovery and Development, Banchi di Sotto 55, 53100 Siena, Italy, Dipartimento Farmaco Chimico Tecnologico, Università di Siena, Via Aldo Moro 53100 Siena, Italy, Dipartimento di Chimica delle Sostanze Naturali (DCSN) e Dipartimento di Chimica Farmaceutica e Tossicologica (DCFT), Università di Napoli “Federico II”, Via D. Montesano 49, 80131 Napoli, Italy, Dipartimento di Scienze Farmaceutiche, Università di Bologna, Via Belmeloro 6, 40126 Bologna, Italy, Neurobiologie
| | - Giuseppe Campiani
- European Research Centre for Drug Discovery and Development, Banchi di Sotto 55, 53100 Siena, Italy, Dipartimento Farmaco Chimico Tecnologico, Università di Siena, Via Aldo Moro 53100 Siena, Italy, Dipartimento di Chimica delle Sostanze Naturali (DCSN) e Dipartimento di Chimica Farmaceutica e Tossicologica (DCFT), Università di Napoli “Federico II”, Via D. Montesano 49, 80131 Napoli, Italy, Dipartimento di Scienze Farmaceutiche, Università di Bologna, Via Belmeloro 6, 40126 Bologna, Italy, Neurobiologie
| | - Ettore Novellino
- European Research Centre for Drug Discovery and Development, Banchi di Sotto 55, 53100 Siena, Italy, Dipartimento Farmaco Chimico Tecnologico, Università di Siena, Via Aldo Moro 53100 Siena, Italy, Dipartimento di Chimica delle Sostanze Naturali (DCSN) e Dipartimento di Chimica Farmaceutica e Tossicologica (DCFT), Università di Napoli “Federico II”, Via D. Montesano 49, 80131 Napoli, Italy, Dipartimento di Scienze Farmaceutiche, Università di Bologna, Via Belmeloro 6, 40126 Bologna, Italy, Neurobiologie
| | - Caterina Fattorusso
- European Research Centre for Drug Discovery and Development, Banchi di Sotto 55, 53100 Siena, Italy, Dipartimento Farmaco Chimico Tecnologico, Università di Siena, Via Aldo Moro 53100 Siena, Italy, Dipartimento di Chimica delle Sostanze Naturali (DCSN) e Dipartimento di Chimica Farmaceutica e Tossicologica (DCFT), Università di Napoli “Federico II”, Via D. Montesano 49, 80131 Napoli, Italy, Dipartimento di Scienze Farmaceutiche, Università di Bologna, Via Belmeloro 6, 40126 Bologna, Italy, Neurobiologie
| | - Bruno Catalanotti
- European Research Centre for Drug Discovery and Development, Banchi di Sotto 55, 53100 Siena, Italy, Dipartimento Farmaco Chimico Tecnologico, Università di Siena, Via Aldo Moro 53100 Siena, Italy, Dipartimento di Chimica delle Sostanze Naturali (DCSN) e Dipartimento di Chimica Farmaceutica e Tossicologica (DCFT), Università di Napoli “Federico II”, Via D. Montesano 49, 80131 Napoli, Italy, Dipartimento di Scienze Farmaceutiche, Università di Bologna, Via Belmeloro 6, 40126 Bologna, Italy, Neurobiologie
| | - Salvatore Sanna Coccone
- European Research Centre for Drug Discovery and Development, Banchi di Sotto 55, 53100 Siena, Italy, Dipartimento Farmaco Chimico Tecnologico, Università di Siena, Via Aldo Moro 53100 Siena, Italy, Dipartimento di Chimica delle Sostanze Naturali (DCSN) e Dipartimento di Chimica Farmaceutica e Tossicologica (DCFT), Università di Napoli “Federico II”, Via D. Montesano 49, 80131 Napoli, Italy, Dipartimento di Scienze Farmaceutiche, Università di Bologna, Via Belmeloro 6, 40126 Bologna, Italy, Neurobiologie
| | - Sindu Ros
- European Research Centre for Drug Discovery and Development, Banchi di Sotto 55, 53100 Siena, Italy, Dipartimento Farmaco Chimico Tecnologico, Università di Siena, Via Aldo Moro 53100 Siena, Italy, Dipartimento di Chimica delle Sostanze Naturali (DCSN) e Dipartimento di Chimica Farmaceutica e Tossicologica (DCFT), Università di Napoli “Federico II”, Via D. Montesano 49, 80131 Napoli, Italy, Dipartimento di Scienze Farmaceutiche, Università di Bologna, Via Belmeloro 6, 40126 Bologna, Italy, Neurobiologie
| | - Giuseppe Borrelli
- European Research Centre for Drug Discovery and Development, Banchi di Sotto 55, 53100 Siena, Italy, Dipartimento Farmaco Chimico Tecnologico, Università di Siena, Via Aldo Moro 53100 Siena, Italy, Dipartimento di Chimica delle Sostanze Naturali (DCSN) e Dipartimento di Chimica Farmaceutica e Tossicologica (DCFT), Università di Napoli “Federico II”, Via D. Montesano 49, 80131 Napoli, Italy, Dipartimento di Scienze Farmaceutiche, Università di Bologna, Via Belmeloro 6, 40126 Bologna, Italy, Neurobiologie
| | - Marco Persico
- European Research Centre for Drug Discovery and Development, Banchi di Sotto 55, 53100 Siena, Italy, Dipartimento Farmaco Chimico Tecnologico, Università di Siena, Via Aldo Moro 53100 Siena, Italy, Dipartimento di Chimica delle Sostanze Naturali (DCSN) e Dipartimento di Chimica Farmaceutica e Tossicologica (DCFT), Università di Napoli “Federico II”, Via D. Montesano 49, 80131 Napoli, Italy, Dipartimento di Scienze Farmaceutiche, Università di Bologna, Via Belmeloro 6, 40126 Bologna, Italy, Neurobiologie
| | - Isabella Fiorini
- European Research Centre for Drug Discovery and Development, Banchi di Sotto 55, 53100 Siena, Italy, Dipartimento Farmaco Chimico Tecnologico, Università di Siena, Via Aldo Moro 53100 Siena, Italy, Dipartimento di Chimica delle Sostanze Naturali (DCSN) e Dipartimento di Chimica Farmaceutica e Tossicologica (DCFT), Università di Napoli “Federico II”, Via D. Montesano 49, 80131 Napoli, Italy, Dipartimento di Scienze Farmaceutiche, Università di Bologna, Via Belmeloro 6, 40126 Bologna, Italy, Neurobiologie
| | - Vito Nacci
- European Research Centre for Drug Discovery and Development, Banchi di Sotto 55, 53100 Siena, Italy, Dipartimento Farmaco Chimico Tecnologico, Università di Siena, Via Aldo Moro 53100 Siena, Italy, Dipartimento di Chimica delle Sostanze Naturali (DCSN) e Dipartimento di Chimica Farmaceutica e Tossicologica (DCFT), Università di Napoli “Federico II”, Via D. Montesano 49, 80131 Napoli, Italy, Dipartimento di Scienze Farmaceutiche, Università di Bologna, Via Belmeloro 6, 40126 Bologna, Italy, Neurobiologie
| | - Pierfranco Ioan
- European Research Centre for Drug Discovery and Development, Banchi di Sotto 55, 53100 Siena, Italy, Dipartimento Farmaco Chimico Tecnologico, Università di Siena, Via Aldo Moro 53100 Siena, Italy, Dipartimento di Chimica delle Sostanze Naturali (DCSN) e Dipartimento di Chimica Farmaceutica e Tossicologica (DCFT), Università di Napoli “Federico II”, Via D. Montesano 49, 80131 Napoli, Italy, Dipartimento di Scienze Farmaceutiche, Università di Bologna, Via Belmeloro 6, 40126 Bologna, Italy, Neurobiologie
| | - Alberto Chiarini
- European Research Centre for Drug Discovery and Development, Banchi di Sotto 55, 53100 Siena, Italy, Dipartimento Farmaco Chimico Tecnologico, Università di Siena, Via Aldo Moro 53100 Siena, Italy, Dipartimento di Chimica delle Sostanze Naturali (DCSN) e Dipartimento di Chimica Farmaceutica e Tossicologica (DCFT), Università di Napoli “Federico II”, Via D. Montesano 49, 80131 Napoli, Italy, Dipartimento di Scienze Farmaceutiche, Università di Bologna, Via Belmeloro 6, 40126 Bologna, Italy, Neurobiologie
| | - Michel Hamon
- European Research Centre for Drug Discovery and Development, Banchi di Sotto 55, 53100 Siena, Italy, Dipartimento Farmaco Chimico Tecnologico, Università di Siena, Via Aldo Moro 53100 Siena, Italy, Dipartimento di Chimica delle Sostanze Naturali (DCSN) e Dipartimento di Chimica Farmaceutica e Tossicologica (DCFT), Università di Napoli “Federico II”, Via D. Montesano 49, 80131 Napoli, Italy, Dipartimento di Scienze Farmaceutiche, Università di Bologna, Via Belmeloro 6, 40126 Bologna, Italy, Neurobiologie
| | - Alfredo Cagnotto
- European Research Centre for Drug Discovery and Development, Banchi di Sotto 55, 53100 Siena, Italy, Dipartimento Farmaco Chimico Tecnologico, Università di Siena, Via Aldo Moro 53100 Siena, Italy, Dipartimento di Chimica delle Sostanze Naturali (DCSN) e Dipartimento di Chimica Farmaceutica e Tossicologica (DCFT), Università di Napoli “Federico II”, Via D. Montesano 49, 80131 Napoli, Italy, Dipartimento di Scienze Farmaceutiche, Università di Bologna, Via Belmeloro 6, 40126 Bologna, Italy, Neurobiologie
| | - Tiziana Mennini
- European Research Centre for Drug Discovery and Development, Banchi di Sotto 55, 53100 Siena, Italy, Dipartimento Farmaco Chimico Tecnologico, Università di Siena, Via Aldo Moro 53100 Siena, Italy, Dipartimento di Chimica delle Sostanze Naturali (DCSN) e Dipartimento di Chimica Farmaceutica e Tossicologica (DCFT), Università di Napoli “Federico II”, Via D. Montesano 49, 80131 Napoli, Italy, Dipartimento di Scienze Farmaceutiche, Università di Bologna, Via Belmeloro 6, 40126 Bologna, Italy, Neurobiologie
| | - Claudia Fracasso
- European Research Centre for Drug Discovery and Development, Banchi di Sotto 55, 53100 Siena, Italy, Dipartimento Farmaco Chimico Tecnologico, Università di Siena, Via Aldo Moro 53100 Siena, Italy, Dipartimento di Chimica delle Sostanze Naturali (DCSN) e Dipartimento di Chimica Farmaceutica e Tossicologica (DCFT), Università di Napoli “Federico II”, Via D. Montesano 49, 80131 Napoli, Italy, Dipartimento di Scienze Farmaceutiche, Università di Bologna, Via Belmeloro 6, 40126 Bologna, Italy, Neurobiologie
| | - Milena Colovic
- European Research Centre for Drug Discovery and Development, Banchi di Sotto 55, 53100 Siena, Italy, Dipartimento Farmaco Chimico Tecnologico, Università di Siena, Via Aldo Moro 53100 Siena, Italy, Dipartimento di Chimica delle Sostanze Naturali (DCSN) e Dipartimento di Chimica Farmaceutica e Tossicologica (DCFT), Università di Napoli “Federico II”, Via D. Montesano 49, 80131 Napoli, Italy, Dipartimento di Scienze Farmaceutiche, Università di Bologna, Via Belmeloro 6, 40126 Bologna, Italy, Neurobiologie
| | - Silvio Caccia
- European Research Centre for Drug Discovery and Development, Banchi di Sotto 55, 53100 Siena, Italy, Dipartimento Farmaco Chimico Tecnologico, Università di Siena, Via Aldo Moro 53100 Siena, Italy, Dipartimento di Chimica delle Sostanze Naturali (DCSN) e Dipartimento di Chimica Farmaceutica e Tossicologica (DCFT), Università di Napoli “Federico II”, Via D. Montesano 49, 80131 Napoli, Italy, Dipartimento di Scienze Farmaceutiche, Università di Bologna, Via Belmeloro 6, 40126 Bologna, Italy, Neurobiologie
| | - Stefania Butini
- European Research Centre for Drug Discovery and Development, Banchi di Sotto 55, 53100 Siena, Italy, Dipartimento Farmaco Chimico Tecnologico, Università di Siena, Via Aldo Moro 53100 Siena, Italy, Dipartimento di Chimica delle Sostanze Naturali (DCSN) e Dipartimento di Chimica Farmaceutica e Tossicologica (DCFT), Università di Napoli “Federico II”, Via D. Montesano 49, 80131 Napoli, Italy, Dipartimento di Scienze Farmaceutiche, Università di Bologna, Via Belmeloro 6, 40126 Bologna, Italy, Neurobiologie
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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
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Abstract
The 5-HT3 receptor belongs to a family of therapeutically important neurotransmitter-gated receptors whose ligand binding sites are formed by the convergence of six peptide loops (A-F). Here we have mutated 15 amino acid residues in and around loop B of the 5-HT3 receptor (Ser-177 to Asn-191) to Ala or a residue with similar chemical properties. Changes in [3H]granisetron binding affinity (Kd) and 5-HT EC50 were determined using receptors expressed in human embryonic kidney 293 cells. Substitutions at all but one residue (Thr-181) altered or eliminated binding for one or both mutants. Receptors were nonfunctional or EC50 values were altered for all but two mutants (S182T, I190L). Homology modeling indicates that loop B contributes two residues to a hydrophobic core that faces into the β-sandwich of the subunit, and the experimental data indicate that they are important for both the structure and the function of the receptor. The models also show that close to the apex of the loop (Ser-182 to Ile-190), loop B residues form an extensive network of hydrogen bonds, both with other loop B residues and with adjacent regions of the protein. Overall, the data suggest that loop B has a major role in maintaining the structure of the region by a series of noncovalent interactions that are easily disrupted by amino acid substitutions.
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25
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Modica MN, Romeo G, Salerno L, Pittalà V, Siracusa MA, Mereghetti I, Cagnotto A, Mennini T, Gáspár R, Gál A, Falkay G, Palkó M, Maksay G, Fülöp F. Synthesis and Receptor Binding of New Thieno[2,3-d]-pyrimidines as Selective Ligands of 5-HT3Receptors. Arch Pharm (Weinheim) 2008; 341:333-43. [DOI: 10.1002/ardp.200700205] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Gao H, Buchapudi KR, Harms-Smyth A, Schulte MK, Xu X, Ji HF. Improved surface modification approach for micromechanical biosensors. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:345-9. [PMID: 18154314 PMCID: PMC3633073 DOI: 10.1021/la7030973] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
We have investigated the sensing performance of protein-based microcantilever biosensors prepared from multiple surface conjugation chemistries. The 11-mercaptoundecanoic acid monolayers were prepared according to both traditional and modified processes. In three protein-based biosensors, the modified process improved microcantilever sensing performance by increasing the bending amplitude, a critical step toward developing a cost-effective microcantilever-based sensor platform for medical diagnostics and environmental and drug screening applications. Scanning electron microscopy (SEM) images demonstrated that proteins immobilized on the microcantilever surface using the modified chemistry approach formed a compact layer.
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Affiliation(s)
- Hongyan Gao
- Chemistry, Institute for Micromanufacturing, Louisiana Tech University, Ruston, Louisiana 71272
| | - Koutilya R. Buchapudi
- Chemistry, Institute for Micromanufacturing, Louisiana Tech University, Ruston, Louisiana 71272
| | - Abraham Harms-Smyth
- Department of Chemistry & Biochemistry, University of Alaska—Fairbanks, Fairbanks, Alaska 99775-6160
| | - Marvin K. Schulte
- Department of Chemistry & Biochemistry, University of Alaska—Fairbanks, Fairbanks, Alaska 99775-6160
| | - Xiaohe Xu
- Chemistry, Institute for Micromanufacturing, Louisiana Tech University, Ruston, Louisiana 71272
| | - Hai-Feng Ji
- Chemistry, Institute for Micromanufacturing, Louisiana Tech University, Ruston, Louisiana 71272
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Maksay G, Bíró T, Laube B, Nemes P. Hyperekplexia mutation R271L of alpha1 glycine receptors potentiates allosteric interactions of nortropeines, propofol and glycine with [3H]strychnine binding. Neurochem Int 2007; 52:235-40. [PMID: 17655979 DOI: 10.1016/j.neuint.2007.06.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2007] [Revised: 06/11/2007] [Accepted: 06/14/2007] [Indexed: 10/23/2022]
Abstract
Human alpha1 and hyperekplexia mutant alpha1(R271L) glycine receptors (GlyRs) were transiently expressed in human embryonic kidney 293 cells for [3H]strychnine binding. Binding parameters were determined using a ternary allosteric model. The hyperekplexia mutation increased the positive cooperativity of 0.3 mM propofol and glycine binding by about six times: the cooperativity factor beta was 0.26 for alpha1 GlyRs and 0.04 for alpha1(R271L) GlyRs. Thus, propofol restored the potency of glycine impaired by the mutation. Five nortropeines, i.e. substituted benzoates of nortropine and a new compound, nortropisetron were prepared and also examined on [3H]strychnine binding. They showed nanomolar displacing potencies amplified by the hyperekplexia mutation. The affinity of nor-O-zatosetron (2.6 nM) is one of the highest reported for GlyRs. This binding test offers an in vitro method to evaluate agents against neurological disorders associated with inherited mutations of GlyRs.
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Affiliation(s)
- Gábor Maksay
- Department of Molecular Pharmacology, Institute of Biomolecular Chemistry, Chemical Research Center, Hungarian Academy of Sciences, H-1525 Budapest, POB 17, Hungary.
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