1
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Kenakin T. Know your molecule: pharmacological characterization of drug candidates to enhance efficacy and reduce late-stage attrition. Nat Rev Drug Discov 2024:10.1038/s41573-024-00958-9. [PMID: 38890494 DOI: 10.1038/s41573-024-00958-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/23/2024] [Indexed: 06/20/2024]
Abstract
Despite advances in chemical, computational and biological sciences, the rate of attrition of drug candidates in clinical development is still high. A key point in the small-molecule discovery process that could provide opportunities to help address this challenge is the pharmacological characterization of hit and lead compounds, culminating in the selection of a drug candidate. Deeper characterization is increasingly important, because the 'quality' of drug efficacy, at least for G protein-coupled receptors (GPCRs), is now understood to be much more than activation of commonly evaluated pathways such as cAMP signalling, with many more 'efficacies' of ligands that could be harnessed therapeutically. Such characterization is being enabled by novel assays to characterize the complex behaviour of GPCRs, such as biased signalling and allosteric modulation, as well as advances in structural biology, such as cryo-electron microscopy. This article discusses key factors in the assessments of the pharmacology of hit and lead compounds in the context of GPCRs as a target class, highlighting opportunities to identify drug candidates with the potential to address limitations of current therapies and to improve the probability of them succeeding in clinical development.
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Affiliation(s)
- Terry Kenakin
- Department of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, NC, USA.
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2
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Kenakin T. Allostery: The Good, the Bad, and the Ugly. J Pharmacol Exp Ther 2024; 388:110-120. [PMID: 37918859 DOI: 10.1124/jpet.123.001838] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Revised: 10/05/2023] [Accepted: 10/13/2023] [Indexed: 11/04/2023] Open
Abstract
With the advent of functional screening, more allosteric molecules are being discovered and developed as possible therapeutic entities. Allosteric proteins are unique because of two specific properties: 1) separate binding sites for allosteric modulators and guests and 2) mandatory alteration of receptor conformation upon binding of allosteric modulators. For G protein-coupled receptors, these properties produce many beneficial effects on pharmacologic systems that are described here. Allosteric discovery campaigns also bring with them added considerations that must be addressed for the endeavor to be successful, and these are described herein as well. SIGNIFICANCE STATEMENT: Recent years have seen the increasing presence of allosteric molecules as possible therapeutic drug candidates. The scientific procedures to characterize these are unique and require special techniques, so it is imperative that scientists understand the new concepts involved in allosteric function. This review examines the reasons why allosteric molecules should be considered as new drug entities and the techniques required to optimize the discovery process for allosteric molecules.
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Affiliation(s)
- Terry Kenakin
- Department of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, North Carolina
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3
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Mocatta J, Mesoy SM, Dougherty DA, Lummis SCR. 5-HT 3 Receptor MX Helix Contributes to Receptor Function. ACS Chem Neurosci 2022; 13:2338-2345. [PMID: 35867037 PMCID: PMC9354082 DOI: 10.1021/acschemneuro.2c00339] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
![]()
5-HT3 receptors are members of the family
of pentameric
ligand-gated ion channels. Each subunit has an extracellular, transmembrane,
and intracellular domain. Only part of the intracellular domain structure
has been solved, revealing it contains two α-helical segments;
one, the MA helix, is an extension of M4, while the other, the MX
helix, is formed from residues located close to the end of M3. This
MX helix is in distinct locations in open and closed receptor structures,
suggesting it may play a role in function. Here, we explore this hypothesis
using functional responses of Ala-substituted mutant receptors expressed
in HEK293 cells. The data show altering many of the MX residues results
in a small decrease in EC50 (up to 5-fold), although in
one (H232A) this is increased. Radiolabeled ligand binding on selected
mutants showed no change in binding affinity, indicating an effect
on gating and not binding. In addition, five mutations (P316A, V317A,
P318A, D319A, and H323A) initially resulted in nonfunctional receptors,
but the function could be rescued by coexpression with a chaperone
protein, suggesting a likely role in assembly or folding. Examination
of previously obtained MD simulation data shows that the extent of
MX encompassed by membrane lipids differs considerably in the open
and closed structures, suggesting that lipid–protein interactions
in this region could have a major effect on channel opening propensity.
We conclude that the MX helix can modulate the function of the receptor
and propose that its interactions with membrane lipids play a major
role in this.
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Affiliation(s)
- James Mocatta
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1GA, United Kingdom
| | - Susanne M Mesoy
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1GA, United Kingdom
| | - Dennis A Dougherty
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Sarah C R Lummis
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1GA, United Kingdom
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4
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Nguyen T, Gamage TF, Finlay DB, Decker AM, Langston TL, Barrus D, Glass M, Li JX, Kenakin TP, Zhang Y. Development of 3-(4-Chlorophenyl)-1-(phenethyl)urea Analogues as Allosteric Modulators of the Cannabinoid Type-1 Receptor: RTICBM-189 is Brain Penetrant and Attenuates Reinstatement of Cocaine-Seeking Behavior. J Med Chem 2021; 65:257-270. [PMID: 34929081 DOI: 10.1021/acs.jmedchem.1c01432] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
We have shown that CB1 receptor negative allosteric modulators (NAMs) attenuated the reinstatement of cocaine-seeking behaviors in rats. In an effort to further define the structure-activity relationships and assess the druglike properties of the 3-(4-chlorophenyl)-1-(phenethyl)urea-based CB1 NAMs that we recently reported, we introduced substituents of different electronic properties and sizes to the phenethyl group and evaluated their potency in CB1 calcium mobilization, cAMP, and GTPγS assays. We found that 3-position substitutions such as Cl, F, and Me afforded enhanced CB1 potency, whereas 4-position analogues were generally less potent. The 3-chloro analogue (31, RTICBM-189) showed no activity at >50 protein targets and excellent brain permeation but relatively low metabolic stability in rat liver microsomes. Pharmacokinetic studies in rats confirmed the excellent brain exposure of 31 with a brain/plasma ratio Kp of 2.0. Importantly, intraperitoneal administration of 31 significantly and selectively attenuated the reinstatement of the cocaine-seeking behavior in rats without affecting locomotion.
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Affiliation(s)
- Thuy Nguyen
- Research Triangle Institute, Research Triangle Park, Research Triangle Park, North Carolina 27709, United States
| | - Thomas F Gamage
- Research Triangle Institute, Research Triangle Park, Research Triangle Park, North Carolina 27709, United States
| | - David B Finlay
- Department of Pharmacology and Toxicology, School of Biomedical Sciences, University of Otago, Dunedin 9054, New Zealand
| | - Ann M Decker
- Research Triangle Institute, Research Triangle Park, Research Triangle Park, North Carolina 27709, United States
| | - Tiffany L Langston
- Research Triangle Institute, Research Triangle Park, Research Triangle Park, North Carolina 27709, United States
| | - Daniel Barrus
- Research Triangle Institute, Research Triangle Park, Research Triangle Park, North Carolina 27709, United States
| | - Michelle Glass
- Department of Pharmacology and Toxicology, School of Biomedical Sciences, University of Otago, Dunedin 9054, New Zealand
| | - Jun-Xu Li
- Department of Pharmacology and Toxicology, University at Buffalo, the State University of New York, Buffalo, New York 14214, United States
| | - Terry P Kenakin
- Department of Pharmacology, University of North Carolina, Chapel Hill, North Carolina 27599, United States
| | - Yanan Zhang
- Research Triangle Institute, Research Triangle Park, Research Triangle Park, North Carolina 27709, United States
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5
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Crnjar A, Mesoy SM, Lummis SCR, Molteni C. A Single Mutation in the Outer Lipid-Facing Helix of a Pentameric Ligand-Gated Ion Channel Affects Channel Function Through a Radially-Propagating Mechanism. Front Mol Biosci 2021; 8:644720. [PMID: 33996899 PMCID: PMC8119899 DOI: 10.3389/fmolb.2021.644720] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Accepted: 02/22/2021] [Indexed: 11/13/2022] Open
Abstract
Pentameric ligand-gated ion channels (pLGICs) mediate fast synaptic transmission and are crucial drug targets. Their gating mechanism is triggered by ligand binding in the extracellular domain that culminates in the opening of a hydrophobic gate in the transmembrane domain. This domain is made of four α-helices (M1 to M4). Recently the outer lipid-facing helix (M4) has been shown to be key to receptor function, however its role in channel opening is still poorly understood. It could act through its neighboring helices (M1/M3), or via the M4 tip interacting with the pivotal Cys-loop in the extracellular domain. Mutation of a single M4 tyrosine (Y441) to alanine renders one pLGIC-the 5-HT3A receptor-unable to function despite robust ligand binding. Using Y441A as a proxy for M4 function, we here predict likely paths of Y441 action using molecular dynamics, and test these predictions with functional assays of mutant receptors in HEK cells and Xenopus oocytes using fluorescent membrane potential sensitive dye and two-electrode voltage clamp respectively. We show that Y441 does not act via the M4 tip or Cys-loop, but instead connects radially through M1 to a residue near the ion channel hydrophobic gate on the pore-lining helix M2. This demonstrates the active role of the M4 helix in channel opening.
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Affiliation(s)
| | - Susanne M. Mesoy
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - Sarah C. R. Lummis
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - Carla Molteni
- Physics Department, King's College London, London, United Kingdom
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6
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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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7
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Basak S, Kumar A, Ramsey S, Gibbs E, Kapoor A, Filizola M, Chakrapani S. High-resolution structures of multiple 5-HT 3AR-setron complexes reveal a novel mechanism of competitive inhibition. eLife 2020; 9:e57870. [PMID: 33063666 PMCID: PMC7655109 DOI: 10.7554/elife.57870] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Accepted: 10/15/2020] [Indexed: 12/13/2022] Open
Abstract
Serotonin receptors (5-HT3AR) play a crucial role in regulating gut movement, and are the principal target of setrons, a class of high-affinity competitive antagonists, used in the management of nausea and vomiting associated with radiation and chemotherapies. Structural insights into setron-binding poses and their inhibitory mechanisms are just beginning to emerge. Here, we present high-resolution cryo-EM structures of full-length 5-HT3AR in complex with palonosetron, ondansetron, and alosetron. Molecular dynamic simulations of these structures embedded in a fully-hydrated lipid environment assessed the stability of ligand-binding poses and drug-target interactions over time. Together with simulation results of apo- and serotonin-bound 5-HT3AR, the study reveals a distinct interaction fingerprint between the various setrons and binding-pocket residues that may underlie their diverse affinities. In addition, varying degrees of conformational change in the setron-5-HT3AR structures, throughout the channel and particularly along the channel activation pathway, suggests a novel mechanism of competitive inhibition.
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Affiliation(s)
- Sandip Basak
- Department of Physiology and Biophysics, Case Western Reserve UniversityClevelandUnited States
- Cleveland Center for Membrane and Structural Biology, Case Western Reserve UniversityClevelandUnited States
| | - Arvind Kumar
- Department of Physiology and Biophysics, Case Western Reserve UniversityClevelandUnited States
- Cleveland Center for Membrane and Structural Biology, Case Western Reserve UniversityClevelandUnited States
| | - Steven Ramsey
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount SinaiNew YorkUnited States
| | - Eric Gibbs
- Department of Physiology and Biophysics, Case Western Reserve UniversityClevelandUnited States
- Cleveland Center for Membrane and Structural Biology, Case Western Reserve UniversityClevelandUnited States
| | - Abhijeet Kapoor
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount SinaiNew YorkUnited States
| | - Marta Filizola
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount SinaiNew YorkUnited States
| | - Sudha Chakrapani
- Department of Physiology and Biophysics, Case Western Reserve UniversityClevelandUnited States
- Cleveland Center for Membrane and Structural Biology, Case Western Reserve UniversityClevelandUnited States
- Department of Neuroscience, School of Medicine, Case Western Reserve UniversityClevelandUnited States
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8
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Zarkadas E, Zhang H, Cai W, Effantin G, Perot J, Neyton J, Chipot C, Schoehn G, Dehez F, Nury H. The Binding of Palonosetron and Other Antiemetic Drugs to the Serotonin 5-HT3 Receptor. Structure 2020; 28:1131-1140.e4. [DOI: 10.1016/j.str.2020.07.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Revised: 06/18/2020] [Accepted: 07/08/2020] [Indexed: 12/19/2022]
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9
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Sasaki Y, Sato Y, Takahashi T, Umetsu M, Iki N. Capillary electrophoretic reactor for estimation of spontaneous dissociation rate of Trypsin-Aprotinin complex. Anal Biochem 2019; 585:113406. [PMID: 31445899 DOI: 10.1016/j.ab.2019.113406] [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] [Received: 06/26/2019] [Revised: 08/19/2019] [Accepted: 08/21/2019] [Indexed: 11/25/2022]
Abstract
A capillary electrophoretic reactor was used to analyze the dissociation kinetics of an enzyme-inhibitor complex in a homogeneous solution without immobilization. The complex consisting of trypsin (Try) and aprotinin (Apr) was used as the model. Capillary electrophoresis provided a reaction field for Try-Apr complex to dissociate through the steady removal of free Try and Apr from the Try-Apr zone. By analyzing the dependence of peak height of Try-Apr on separation time, the dissociation rate kdH was obtained as 2.73 × 10-4 s-1 (298 K) at pH 2.46. The dependence of kdH on the proton concentration (pH = 2.09-3.12) revealed a first-order dependence of kdH on [H+]; kdH = kd + k1[H+], where kd is the spontaneous dissociation rate and was 5.65 × 10-5 s-1, and k1 is the second-order rate constant and was 5.07 × 10-2 M-1 s-1. From the kd value, the half-life of the Try-Apr complex at physiological pH was determined as 3.4 h. The presence of the proton-assisted dissociation can be explained by the protonation of -COO- of the Asp residue in Try, which breaks the salt bridge with the -NH3+ group of Lys in Apr.
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Affiliation(s)
- Yumiko Sasaki
- Graduate School of Environmental Studies, Tohoku University, 6-6-07 Aramaki-Aoba, Aoba, Sendai, 980-8579, Japan
| | - Yosuke Sato
- Graduate School of Environmental Studies, Tohoku University, 6-6-07 Aramaki-Aoba, Aoba, Sendai, 980-8579, Japan
| | - Toru Takahashi
- Graduate School of Engineering, University of Fukui, 3-9-1 Bunkyo, Fukui, 910-8507, Japan
| | - Mitsuo Umetsu
- Graduate School of Engineering, Tohoku University, 6-6-11 Aramaki-Aoba, Aoba, Sendai, 980-8579, Japan
| | - Nobuhiko Iki
- Graduate School of Environmental Studies, Tohoku University, 6-6-07 Aramaki-Aoba, Aoba, Sendai, 980-8579, Japan.
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10
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G-Protein/Receptor inhibitors as blockers of receptor signaling. J Theor Biol 2019; 480:23-33. [PMID: 31356763 DOI: 10.1016/j.jtbi.2019.07.014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Revised: 07/23/2019] [Accepted: 07/26/2019] [Indexed: 11/23/2022]
Abstract
This paper describes the behavior of binding and functional receptor systems where an antagonist of the receptor/G protein binding reaction is added as a blocker of agonist-induced receptor function. For agonist radioligands, the reduction of G protein receptor interaction leads to a possible change in the binding affinity of the agonist radioligand to the receptor. Reciprocally, the allosteric cooperativity between the agonist and the G protein binding site antagonist (quantified by the factor γB) affects the potency of the G protein antagonist modulator; this model presents the various profiles that would be expected for modulators that reduce (γB = 0.01), have no effect on (γB = 1) and increase (γB = 100) the affinity of the agonist for the receptor. It will be seen that modulators that increase the affinity of the receptor for the agonist are the most potent antagonists and may attain a profile of some special negative allosteric modulators referred to as PAM antagonists. In all cases, these modulators will be inverse agonists of constitutive receptor activity. This model presents a strategy for the discovery of PAM antagonists for therapeutic blockade of physiological signaling.
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11
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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: 33] [Impact Index Per Article: 6.6] [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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12
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Mesoy S, Jeffreys J, Lummis SCR. Characterization of Residues in the 5-HT 3 Receptor M4 Region That Contribute to Function. ACS Chem Neurosci 2019; 10:3167-3172. [PMID: 30835437 DOI: 10.1021/acschemneuro.8b00603] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
5-HT3 receptors are members of the family of pentameric ligand gated ion channels (pLGICs). Each subunit has four transmembrane α-helices (M1-M4), with M4 being most distant from the central pore. Residues in this α-helix interact with adjacent lipids and the neighboring M1 and M3 helices, contributing to both receptor assembly and channel function. This study probes the role of each M4 receptor residue in the 5-HT3A receptor using mutagenesis and subsequent expression in HEK293 cells, probing functional parameters using fluorescence membrane potential sensitive dye. The data show that only one residue in M4 (Y441) and two flanking residues (D434 and W459) result in nonfunctional receptors when substituted with Ala: D434A and W459A-containing receptors ablate expression, while Y441A-containing receptor do not, suggesting the latter is involved in channel gating. Most other altered residues have wild-type-like properties, which is inconsistent with data from other pLGICs. Substitution of Y441 and W459 with other aromatics restores function, suggesting the π ring is important. Further substitutions indicate interactions of Y441 with D238 in M1, W459 with F144 in the Cys loop, and D434 with R251 in M2, data consistent with recently published structures. These regions are critical for transducing binding into gating, and thus interactions of these residues can explain their importance in the function of the 5-HT3 receptor. We also conclude that the small number of critical M4 residues compared to related receptors supports the hypothesis that M4 does not behave identically in all pLGICs.
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Affiliation(s)
- Susanne Mesoy
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB 1QW, United Kingdom
| | - Jennifer Jeffreys
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB 1QW, United Kingdom
| | - Sarah C. R. Lummis
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB 1QW, United Kingdom
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13
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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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14
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PAM-Antagonists: A Better Way to Block Pathological Receptor Signaling? Trends Pharmacol Sci 2018; 39:748-765. [PMID: 29885909 DOI: 10.1016/j.tips.2018.05.001] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Revised: 04/27/2018] [Accepted: 05/01/2018] [Indexed: 12/20/2022]
Abstract
Seven transmembrane receptor (7TMR) responses are modulated by orthosteric and allosteric ligands to great therapeutic advantage. Here we introduce a unique class of negative allosteric modulator (NAM) - the positive allosteric modulator (PAM)-antagonist - that increases the affinity of the receptor for the agonist but concomitantly decreases agonist efficacy when cobound. Notably, the reciprocation of allosteric energy causes the orthosteric agonist to increase the affinity of the receptor for the PAM-antagonist; thus, this modulator seeks out and destroys agonist-bound receptor complexes. When contrasted with standard orthosteric and allosteric antagonists it is clear that PAM-antagonists are uniquely well suited to reversing ongoing persistent agonism and provide favorable target coverage in vivo. Specifically, the therapeutic application of PAM-antagonists to reverse pathological overactivation (e.g., endothelin vasoconstriction) is emphasized.
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15
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Yaakob NS, Nguyen DT, Exintaris B, Irving HR. The C and E subunits of the serotonin 5-HT 3 receptor subtly modulate electrical properties of the receptor. Biomed Pharmacother 2018; 97:1701-1709. [PMID: 29793334 DOI: 10.1016/j.biopha.2017.12.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Revised: 11/24/2017] [Accepted: 12/04/2017] [Indexed: 12/13/2022] Open
Abstract
Serotonin type 3 (5-hydroxytrptamine-3, 5-HT3) receptors are ligand-gated cation channels present in both central and peripheral nervous systems. In humans there are five different subunits (A, B, C, D and E) of 5-HT3 receptors which can form homomeric or heteromeric receptors that may account for discrepancies in patient responses to treatments. The present study commences characterisation of the profiles of human 5-HT3 receptors containing C and/or E subunits. Recombinant 5-HT3 receptors were expressed transiently in HEK293T cells and expression was checked via immunocytochemistry staining against each epitope-tagged subunits. Functional characterisation of different combinations of 5-HT3 receptor complexes was studied via patch clamp whole cell recordings. In this study, increased current was seen in cells containing A and C subunits but only subtle changes were seen in the electrical properties of cells expressing A, AE, or ACE subunits in response to the ligand, 5-HT. Both di- and tri-heteromeric 5-HT3 receptors were significantly inhibited by the antagonists, ondansetron and palonosetron. Notably, palonosetron exerted stronger and more rapid inhibition on the 5-HT3 receptor ACE tri-heteromer compared to homomeric and di-heteromeric counterparts. This study demonstrated that the C and E subunits when assembled as simple or complex heteromeric 5-HT3 receptors may alter efficacies of 5-HT and clinically used antagonists such as ondansetron and palonosetron, and this in turn may have implications for patient responses to therapies.
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Affiliation(s)
- Nor Syafinaz Yaakob
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University (Parkville Campus), 381 Royal Parade, Parkville, VIC 3052, Australia
| | - Dan-Thanh Nguyen
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University (Parkville Campus), 381 Royal Parade, Parkville, VIC 3052, Australia
| | - Betty Exintaris
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University (Parkville Campus), 381 Royal Parade, Parkville, VIC 3052, Australia
| | - Helen Ruth Irving
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University (Parkville Campus), 381 Royal Parade, Parkville, VIC 3052, Australia.
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Riga MS, Teruel-Martí V, Sánchez C, Celada P, Artigas F. Subchronic vortioxetine treatment –but not escitalopram– enhances pyramidal neuron activity in the rat prefrontal cortex. Neuropharmacology 2017; 113:148-155. [DOI: 10.1016/j.neuropharm.2016.09.024] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Revised: 09/12/2016] [Accepted: 09/22/2016] [Indexed: 12/25/2022]
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17
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Price KL, Lillestol RK, Ulens C, Lummis SCR. Palonosetron-5-HT 3 Receptor Interactions As Shown by a Binding Protein Cocrystal Structure. ACS Chem Neurosci 2016; 7:1641-1646. [PMID: 27656911 DOI: 10.1021/acschemneuro.6b00132] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Palonosetron is a potent 5-HT3 receptor antagonist and an effective therapeutic agent against emesis. Here we identify the molecular determinants of compound recognition in the receptor binding site by obtaining a high resolution structure of palonosetron bound to an engineered acetylcholine binding protein that mimics the 5-HT3 receptor binding site, termed 5-HTBP, and by examining the potency of palonosetron in a range of 5-HT3 receptors with mutated binding site residues. The structural data indicate that palonosetron forms a tight and effective wedge in the binding pocket, made possible by its rigid tricyclic ring structure and its interactions with binding site residues; it adopts a binding pose that is distinct from the related antiemetics granisetron and tropisetron. The functional data show many residues previously shown to interact with agonists and antagonists in the binding site are important for palonosetron binding, and indicate those of particular importance are W183 (a cation-π interaction and a hydrogen bond) and Y153 (a hydrogen bond). This information, and the availability of the structure of palonosetron bound to 5-HTBP, should aid the development of novel and more efficacious drugs that act via 5-HT3 receptors.
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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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18
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Mu L, Müller Herde A, Rüefli PM, Sladojevich F, Milicevic Sephton S, Krämer SD, Thompson AJ, Schibli R, Ametamey SM, Lochner M. Synthesis and Pharmacological Evaluation of [ 11C]Granisetron and [ 18F]Fluoropalonosetron as PET Probes for 5-HT 3 Receptor Imaging. ACS Chem Neurosci 2016; 7:1552-1564. [PMID: 27571447 DOI: 10.1021/acschemneuro.6b00192] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Serotonin-gated ionotropic 5-HT3 receptors are the major pharmacological targets for antiemetic compounds. Furthermore, they have become a focus for the treatment of irritable bowel syndrome (IBS) and there is some evidence that pharmacological modulation of 5-HT3 receptors might alleviate symptoms of other neurological disorders. Highly selective, high-affinity antagonists, such as granisetron (Kytril) and palonosetron (Aloxi), belong to a family of drugs (the "setrons") that are well established for clinical use. To enable us to better understand the actions of these drugs in vivo, we report the synthesis of 8-fluoropalonosetron (15) that has a binding affinity (Ki = 0.26 ± 0.05 nM) similar to the parent drug (Ki = 0.21 ± 0.03 nM). We radiolabeled 15 by nucleophilic 18F-fluorination of an unsymmetrical diaryliodonium palonosetron precursor and achieved the radiosynthesis of 1-(methyl-11C)-N-granisetron ([11C]2) through N-alkylation with [11C]CH3I, respectively. Both compounds [18F]15 (chemical and radiochemical purity >95%, specific activity 41 GBq/μmol) and [11C]2 (chemical and radiochemical purity ≥99%, specific activity 170 GBq/μmol) were evaluated for their utility as positron emission tomography (PET) probes. Using mouse and rat brain slices, in vitro autoradiography with both [18F]15 and [11C]2 revealed a heterogeneous and displaceable binding in cortical and hippocampal regions that are known to express 5-HT3 receptors at significant levels. Subsequent PET experiments suggested that [18F]15 and [11C]2 are of limited utility for the PET imaging of brain 5-HT3 receptors in vivo.
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Affiliation(s)
- Linjing Mu
- Department
of Nuclear Medicine, University Hospital Zürich, Rämistrasse
100, 8091 Zürich, Switzerland
| | - Adrienne Müller Herde
- Center for Radiopharmaceutical
Sciences of ETH, PSI and USZ, Vladimir-Prelog-Weg
4, 8093 Zürich, Switzerland
| | - Pascal M. Rüefli
- Department
of Chemistry and Biochemistry, University of Bern, Freiestrasse
3, 3012 Bern, Switzerland
| | - Filippo Sladojevich
- Center for Radiopharmaceutical
Sciences of ETH, PSI and USZ, Vladimir-Prelog-Weg
4, 8093 Zürich, Switzerland
| | - Selena Milicevic Sephton
- Center for Radiopharmaceutical
Sciences of ETH, PSI and USZ, Vladimir-Prelog-Weg
4, 8093 Zürich, Switzerland
| | - Stefanie D. Krämer
- Center for Radiopharmaceutical
Sciences of ETH, PSI and USZ, Vladimir-Prelog-Weg
4, 8093 Zürich, Switzerland
| | - Andrew J. Thompson
- Department
of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, United Kingdom
| | - Roger Schibli
- Center for Radiopharmaceutical
Sciences of ETH, PSI and USZ, Vladimir-Prelog-Weg
4, 8093 Zürich, Switzerland
| | - Simon M. Ametamey
- Center for Radiopharmaceutical
Sciences of ETH, PSI and USZ, Vladimir-Prelog-Weg
4, 8093 Zürich, Switzerland
| | - Martin Lochner
- Department
of Chemistry and Biochemistry, University of Bern, Freiestrasse
3, 3012 Bern, Switzerland
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Finley M, Cassaday J, Kreamer T, Li X, Solly K, O'Donnell G, Clements M, Converso A, Cook S, Daley C, Kraus R, Lai MT, Layton M, Lemaire W, Staas D, Wang J. Kinetic Analysis of Membrane Potential Dye Response to NaV1.7 Channel Activation Identifies Antagonists with Pharmacological Selectivity against NaV1.5. ACTA ACUST UNITED AC 2016; 21:480-9. [PMID: 26861708 DOI: 10.1177/1087057116629669] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Accepted: 01/08/2016] [Indexed: 11/17/2022]
Abstract
The NaV1.7 voltage-gated sodium channel is a highly valued target for the treatment of neuropathic pain due to its expression in pain-sensing neurons and human genetic mutations in the gene encoding NaV1.7, resulting in either loss-of-function (e.g., congenital analgesia) or gain-of-function (e.g., paroxysmal extreme pain disorder) pain phenotypes. We exploited existing technologies in a novel manner to identify selective antagonists of NaV1.7. A full-deck high-throughput screen was developed for both NaV1.7 and cardiac NaV1.5 channels using a cell-based membrane potential dye FLIPR assay. In assay development, known local anesthetic site inhibitors produced a decrease in maximal response; however, a subset of compounds exhibited a concentration-dependent delay in the onset of the response with little change in the peak of the response at any concentration. Therefore, two methods of analysis were employed for the screen: one to measure peak response and another to measure area under the curve, which would capture the delay-to-onset phenotype. Although a number of compounds were identified by a selective reduction in peak response in NaV1.7 relative to 1.5, the AUC measurement and a subsequent refinement of this measurement were able to differentiate compounds with NaV1.7 pharmacological selectivity over NaV1.5 as confirmed in electrophysiology.
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Affiliation(s)
- Michael Finley
- Merck Research Labs, Screening and Protein Sciences, North Wales, PA, USA
| | - Jason Cassaday
- Merck Research Labs, Screening and Protein Sciences, North Wales, PA, USA
| | - Tony Kreamer
- Merck Research Labs, Screening and Protein Sciences, North Wales, PA, USA
| | - Xinnian Li
- Merck Research Labs, Screening and Protein Sciences, North Wales, PA, USA
| | - Kelli Solly
- Merck Research Labs, Screening and Protein Sciences, North Wales, PA, USA
| | - Greg O'Donnell
- Merck Research Labs, Screening and Protein Sciences, North Wales, PA, USA
| | | | | | - Sean Cook
- Merck Research Labs, Pharmacology, West Point, PA, USA CNS Discovery Research, Teva Pharmaceuticals, West Chester, PA, USA
| | - Chris Daley
- Merck Research Labs, Pharmacology, West Point, PA, USA
| | - Richard Kraus
- Merck Research Labs, Pharmacology, West Point, PA, USA
| | - Ming-Tain Lai
- Merck Research Labs, Pharmacology, West Point, PA, USA
| | - Mark Layton
- Merck Research Labs, Chemistry, West Point, PA, USA
| | - Wei Lemaire
- Merck Research Labs, Pharmacology, West Point, PA, USA
| | - Donnette Staas
- Merck Research Labs, Chemical Modeling and Informatics, West Point, PA, USA
| | - Jixin Wang
- Merck Research Labs, Pharmacology, West Point, PA, USA
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20
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Hothersall JD, Alexander A, Samson AJ, Moffat C, Bollan KA, Connolly CN. 5-Hydroxytryptamine (5-HT) cellular sequestration during chronic exposure delays 5-HT3 receptor resensitization due to its subsequent release. J Biol Chem 2014; 289:32020-32029. [PMID: 25281748 PMCID: PMC4231679 DOI: 10.1074/jbc.m114.594796] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The serotonergic synapse is dynamically regulated by serotonin (5-hydroxytryptamine (5-HT)) with elevated levels leading to the down-regulation of the serotonin transporter and a variety of 5-HT receptors, including the 5-HT type-3 (5-HT3) receptors. We report that recombinantly expressed 5-HT3 receptor binding sites are reduced by chronic exposure to 5-HT (IC50 of 154.0 ± 45.7 μm, t½ = 28.6 min). This is confirmed for 5-HT3 receptor-induced contractions in the guinea pig ileum, which are down-regulated after chronic, but not acute, exposure to 5-HT. The loss of receptor function does not involve endocytosis, and surface receptor levels are unaltered. The rate and extent of down-regulation is potentiated by serotonin transporter function (IC50 of 2.3 ± 1.0 μm, t½ = 3.4 min). Interestingly, the level of 5-HT uptake correlates with the extent of down-regulation. Using TX-114 extraction, we find that accumulated 5-HT remains soluble and not membrane-bound. This cytoplasmically sequestered 5-HT is readily releasable from both COS-7 cells and the guinea pig ileum. Moreover, the 5-HT level released is sufficient to prevent recovery from receptor desensitization in the guinea pig ileum. Together, these findings suggest the existence of a novel mechanism of down-regulation where the chronic release of sequestered 5-HT prolongs receptor desensitization.
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Affiliation(s)
- J Daniel Hothersall
- Medical Research Institute, University of Dundee, Dundee DD1 9SY, Scotland, United Kingdom
| | - Amy Alexander
- Medical Research Institute, University of Dundee, Dundee DD1 9SY, Scotland, United Kingdom
| | - Andrew J Samson
- Medical Research Institute, University of Dundee, Dundee DD1 9SY, Scotland, United Kingdom
| | - Christopher Moffat
- Medical Research Institute, University of Dundee, Dundee DD1 9SY, Scotland, United Kingdom
| | - Karen A Bollan
- Medical Research Institute, University of Dundee, Dundee DD1 9SY, Scotland, United Kingdom
| | - Christopher N Connolly
- Medical Research Institute, University of Dundee, Dundee DD1 9SY, Scotland, United Kingdom.
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21
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Lee KH, Rim SK, Lee JY, Lee SY, Lee SN, Lee EJ, Lee JH. Effects of pretreatment with intravenous palonosetron for propofol-remifentanil-based anesthesia in breast and thyroid cancer surgery: a double-blind, randomized, controlled study. Korean J Anesthesiol 2014; 67:13-9. [PMID: 25097733 PMCID: PMC4121488 DOI: 10.4097/kjae.2014.67.1.13] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2013] [Revised: 11/28/2013] [Accepted: 01/09/2014] [Indexed: 11/17/2022] Open
Abstract
Background We postulated that palonosetron, a novel antiemetic agent, might have the effect of alleviating injection pain from propofol and rocuronium. A double-blind, controlled study was undertaken to evaluate the effect of palonosetron on injection pain during total intravenous anesthesia and postoperative nausea and vomiting (PONV) using propofol-remifentanil in breast and thyroid cancer surgery. Methods Sixty patients were randomly allocated to one of two groups. Before injection of propofol and rocuronium, patients in group S (n = 30) received 4 ml of saline and patients in group P (n = 30) received 75 µg (1.5 ml) of palonosetron mixed with 2.5 ml of saline (n = 30). Patients were evaluated by a blinded anesthesiologist with regard to the scoring of injection pain of propofol, withdrawal response by rocuronium, PONV, shivering, postoperative pain, recall of pain, and overall satisfaction. Results The differences between groups in the incidence of injection pain due to propofol and rocuronium were insignificant. However, in group P, the severity of propofol-induced injection pain (3% vs. 33%, P = 0.003) and postoperative pain (P = 0.038) was significantly lower during the first 12 h after surgery. No differences were observed between the groups with respect to PONV, shivering, recall of pain, and overall satisfaction. Conclusions We concluded that pretreatment of palonosetron was effective to reduce the severity of propofol-induced injection pain and early postoperative pain, although it did not reduce the incidence of injection pain from propofol and rocuronium.
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Affiliation(s)
- Kye Hyeok Lee
- Department of Anesthesiology and Pain Medicine, Korean Cancer Center Hospital, Seoul, Korea
| | - Sung Kyu Rim
- Department of Anesthesiology and Pain Medicine, Korean Cancer Center Hospital, Seoul, Korea
| | - Ji Yeon Lee
- Department of Anesthesiology and Pain Medicine, Korean Cancer Center Hospital, Seoul, Korea
| | - So Young Lee
- Department of Anesthesiology and Pain Medicine, Korean Cancer Center Hospital, Seoul, Korea
| | - Su Nam Lee
- Department of Anesthesiology and Pain Medicine, Korean Cancer Center Hospital, Seoul, Korea
| | - Eun Ju Lee
- Department of Anesthesiology and Pain Medicine, Korean Cancer Center Hospital, Seoul, Korea
| | - Ji Heui Lee
- Department of Anesthesiology and Pain Medicine, Korean Cancer Center Hospital, Seoul, Korea
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22
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Del Cadia M, De Rienzo F, Weston DA, Thompson AJ, Menziani MC, Lummis SC. Exploring a potential palonosetron allosteric binding site in the 5-HT(3) receptor. Bioorg Med Chem 2013; 21:7523-8. [PMID: 24128813 PMCID: PMC3898987 DOI: 10.1016/j.bmc.2013.09.028] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2013] [Revised: 09/10/2013] [Accepted: 09/11/2013] [Indexed: 11/26/2022]
Abstract
Palonosetron (Aloxi) is a potent second generation 5-HT(3) receptor antagonist whose mechanism of action is not yet fully understood. Palonosetron acts at the 5-HT(3) receptor binding site but recent computational studies indicated other possible sites of action in the extracellular domain. To test this hypothesis we mutated a series of residues in the 5-HT3A receptor subunit (Tyr(73), Phe(130), Ser(163), and Asp(165)) and in the 5-HT3B receptor subunit (His(73), Phe(130), Glu(170), and Tyr(143)) that were previously predicted by in silico docking studies to interact with palonosetron. Homomeric (5-HT(3)A) and heteromeric (5-HT(3)AB) receptors were then expressed in HEK293 cells to determine the potency of palonosetron using both fluorimetric and radioligand methods to test function and ligand binding, respectively. The data show that the substitutions have little or no effect on palonosetron inhibition of 5-HT-evoked responses or binding. In contrast, substitutions in the orthosteric binding site abolish palonosetron binding. Overall, the data support a binding site for palonosetron at the classic orthosteric binding pocket between two 5-HT3A receptor subunits but not at allosteric sites previously identified by in silico modelling and docking.
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Affiliation(s)
- Marta Del Cadia
- Dipartimento di Scienze Chimiche e Geologiche, Università degli Studi di Modena e Reggio Emilia, Via Campi 183, 41100 Modena, Italy
| | - Francesca De Rienzo
- Dipartimento di Scienze Chimiche e Geologiche, Università degli Studi di Modena e Reggio Emilia, Via Campi 183, 41100 Modena, Italy
| | - David A. Weston
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QW, UK
| | - Andrew J. Thompson
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QW, UK
| | - Maria Cristina Menziani
- Dipartimento di Scienze Chimiche e Geologiche, Università degli Studi di Modena e Reggio Emilia, Via Campi 183, 41100 Modena, Italy
| | - Sarah C.R. Lummis
- Dipartimento di Scienze Chimiche e Geologiche, Università degli Studi di Modena e Reggio Emilia, Via Campi 183, 41100 Modena, Italy
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QW, UK
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