Browse
Submit Data
Databases
API
Help

Dataset Information

22 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Conformational transitions of the serotonin 5-HT3 receptor.

ABSTRACT: The serotonin 5-HT3 receptor is a pentameric ligand-gated ion channel (pLGIC). It belongs to a large family of receptors that function as allosteric signal transducers across the plasma membrane1,2; upon binding of neurotransmitter molecules to extracellular sites, the receptors undergo complex conformational transitions that result in transient opening of a pore permeable to ions. 5-HT3 receptors are therapeutic targets for emesis and nausea, irritable bowel syndrome and depression3. In spite of several reported pLGIC structures4-8, no clear unifying view has emerged on the conformational transitions involved in channel gating. Here we report four cryo-electron microscopy structures of the full-length mouse 5-HT3 receptor in complex with the anti-emetic drug tropisetron, with serotonin, and with serotonin and a positive allosteric modulator, at resolutions ranging from 3.2 Å to 4.5 Å. The tropisetron-bound structure resembles those obtained with an inhibitory nanobody5 or without ligand9. The other structures include an 'open' state and two ligand-bound states. We present computational insights into the dynamics of the structures, their pore hydration and free-energy profiles, and characterize movements at the gate level and cation accessibility in the pore. Together, these data deepen our understanding of the gating mechanism of pLGICs and capture ligand binding in unprecedented detail.

SUBMITTER: Polovinkin L

PROVIDER: S-EPMC6614044 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Similar Datasets

Azologization of serotonin 5-HT3 receptor antagonists.

Project description:The serotonin 5-hydroxytryptamine 3 receptor (5-HT3R) plays a unique role within the seven classes of the serotonin receptor family, as it represents the only ionotropic receptor, while the other six members are G protein-coupled receptors (GPCRs). The 5-HT3 receptor is related to chemo-/radiotherapy provoked emesis and dysfunction leads to neurodevelopmental disorders and psychopathologies. Since the development of the first serotonin receptor antagonist in the early 1990s, the range of highly selective and potent drugs expanded based on various chemical structures. Nevertheless, on-off-targeting of a pharmacophore's activity with high spatiotemporal resolution as provided by photopharmacology remains an unsolved challenge bearing additionally the opportunity for detailed receptor examination. In the presented work, we summarize the synthesis, photochromic properties and in vitro characterization of azobenzene-based photochromic derivatives of published 5-HT3R antagonists. Despite reported proof of principle of direct azologization, only one of the investigated derivatives showed antagonistic activity lacking isomer specificity.

| S-EPMC6444460 | biostudies-literature

Multivalent ligands for the serotonin 5-HT4 receptor.

Project description:5-HT4 receptors are known to form constitutive dimers in membranes. To explore whether multivalency can enhance ligand interactions and/or efficacy in 5-HT4 receptors, the structure of the partial agonist ML10302 was modified with oligo(ethylene glycol) chains, thus generating, by a gradual approach, short and long tethered bivalent or tetravalent ligands and the corresponding spanner-linked monovalent controls. Both bivalent and tetravalent ligands displayed a 10-20-fold increase in binding affinity compared to appropriate controls, but no multivalent ligand showed greater binding energy than ML10302 itself. Furthermore, the direct assessment of receptor-Gs interaction and studies of cAMP signalling indicated that multivalency does not enhance the efficacy of ML10302.

| S-EPMC6071950 | biostudies-literature

Microsecond-timescale simulations suggest 5-HT-mediated preactivation of the 5-HT3A serotonin receptor.

Project description:Aided by efforts to improve their speed and efficiency, molecular dynamics (MD) simulations provide an increasingly powerful tool to study the structure-function relationship of pentameric ligand-gated ion channels (pLGICs). However, accurate reporting of the channel state and observation of allosteric regulation by agonist binding with MD remains difficult due to the timescales necessary to equilibrate pLGICs from their artificial and crystalized conformation to a more native, membrane-bound conformation in silico. Here, we perform multiple all-atom MD simulations of the homomeric 5-hydroxytryptamine 3A (5-HT3A) serotonin receptor for 15 to 20 μs to demonstrate that such timescales are critical to observe the equilibration of a pLGIC from its crystalized conformation to a membrane-bound conformation. These timescales, which are an order of magnitude longer than any previous simulation of 5-HT3A, allow us to observe the dynamic binding and unbinding of 5-hydroxytryptamine (5-HT) (i.e., serotonin) to the binding pocket located on the extracellular domain (ECD) and allosteric regulation of the transmembrane domain (TMD) from synergistic 5-HT binding. While these timescales are not long enough to observe complete activation of 5-HT3A, the allosteric regulation of ion gating elements by 5-HT binding is indicative of a preactive state, which provides insight into molecular mechanisms that regulate channel activation from a resting state. This mechanistic insight, enabled by microsecond-timescale MD simulations, will allow a careful examination of the regulation of pLGICs at a molecular level, expanding our understanding of their function and elucidating key structural motifs that can be targeted for therapeutic regulation.

| S-EPMC6955379 | biostudies-literature

Synthesis and activity of functionalizable derivatives of the serotonin (5-HT) 5-HT2A receptor (5-HT2AR) antagonist M100907.

Project description:The approach of tethering together two known receptor ligands, to be used as molecular probes for the study of G protein-coupled receptor (GPCR) systems, has proven to be a valuable approach. Selective ligands that possess functionality that can be used to link to other ligands, are useful in the development of novel antagonists and agonists. Such molecules can also be attached to reporter molecules, such as fluorophores, for the study of GPCR dimerization and its role in signaling. The highly selective serotonin (5-HT) 5-HT2A receptor (5-HT2AR) antagonist M100907 (volinanserin) is of clinical interest in the treatment of neurological and mental health disorders. Here, we synthesized the most active (+)-M100907 enantiomer as well as a series of derivatives that possessed either an alkyne or an azide. The triazole resulting from the dipolar cycloaddition of these groups did not interfere with the ability of the bivalent ligand to act as an antagonist. Thus, we have synthesized a number of compounds which will prove useful in elucidating the role of the 5-HT2AR in the central nervous system.

| S-EPMC6613932 | biostudies-literature

Structure of a Hallucinogen-Activated Gq-Coupled 5-HT2A Serotonin Receptor.

Project description:Hallucinogens like lysergic acid diethylamide (LSD), psilocybin, and substituted N-benzyl phenylalkylamines are widely used recreationally with psilocybin being considered as a therapeutic for many neuropsychiatric disorders including depression, anxiety, and substance abuse. How psychedelics mediate their actions-both therapeutic and hallucinogenic-are not understood, although activation of the 5-HT2A serotonin receptor (HTR2A) is key. To gain molecular insights into psychedelic actions, we determined the active-state structure of HTR2A bound to 25-CN-NBOH-a prototypical hallucinogen-in complex with an engineered Gαq heterotrimer by cryoelectron microscopy (cryo-EM). We also obtained the X-ray crystal structures of HTR2A complexed with the arrestin-biased ligand LSD or the inverse agonist methiothepin. Comparisons of these structures reveal determinants responsible for HTR2A-Gαq protein interactions as well as the conformational rearrangements involved in active-state transitions. Given the potential therapeutic actions of hallucinogens, these findings could accelerate the discovery of more selective drugs for the treatment of a variety of neuropsychiatric disorders.

| S-EPMC7593816 | biostudies-literature

Asymmetric opening of the homopentameric 5-HT3A serotonin receptor in lipid bilayers.

Project description:Pentameric ligand-gated ion channels (pLGICs) of the Cys-loop receptor family are key players in fast signal transduction throughout the nervous system. They have been shown to be modulated by the lipid environment, however the underlying mechanism is not well understood. We report three structures of the Cys-loop 5-HT3A serotonin receptor (5HT3R) reconstituted into saposin-based lipid bilayer discs: a symmetric and an asymmetric apo state, and an asymmetric agonist-bound state. In comparison to previously published 5HT3R conformations in detergent, the lipid bilayer stabilises the receptor in a more tightly packed, 'coupled' state, involving a cluster of highly conserved residues. In consequence, the agonist-bound receptor conformation adopts a wide-open pore capable of conducting sodium ions in unbiased molecular dynamics (MD) simulations. Taken together, we provide a structural basis for the modulation of 5HT3R by the membrane environment, and a model for asymmetric activation of the receptor.

| S-EPMC7887223 | biostudies-literature

Development of subnanomolar-affinity serotonin 5-HT4 receptor ligands based on quinoline structures.

Project description:Two small series of quinoline derivatives were designed starting from previously published quinoline derivatives 7a and b in order to obtain information about their interaction with the 5-HT4R binding site. Initially, the structure of 7a and b was modified by replacing their basic moiety with that of partial agonist 4 (ML10302) or with that of reference ligand 6 (RS-67-333). Then, the aromatic moieties of 4-quinolinecarboxylates 7a, d-f, and h-k or 4-quinolinecarboxamides 7b, c, and g were modified into those of 2-quinolinecarboxamides 9a-e. Very interestingly, this structure-affinity relationship study led to the discovery of 7h-j as novel 5-HT4R ligands showing K i values in the subnanomolar range. The structures of all these compounds contain the N-butyl-4-piperidinylmethyl substituent, which appear to behave as an optimized basic moiety in the interaction of these 4-quinolinecarboxylates with the 5-HT4R binding site. However, this basic moiety was ineffective in providing 5-HT4R affinity in the corresponding 4-quinolinecarboxamide 7g, but it did in 2-quinolinecarboxamide ligands 9c-e. Thus, a subtle interrelationship of several structural parameters appeared to play a major role in the interaction of the ligands with the 5-HT4R binding site. They include the kind of basic moiety, the position of the carbonyl linking group with respect to the aromatic moiety and its orientation, which could be affected by the presence of the intramolecular H-bond as in compounds 9c-e.

| S-EPMC6148519 | biostudies-literature

Serotonin 5-HT1B receptor-mediated behavior and binding in mice with the overactive and dysregulated serotonin transporter Ala56 variant.

Project description:RationaleElevated whole-blood serotonin (5-HT) is a robust biomarker in ~ 30% of patients with autism spectrum disorders, in which repetitive behavior is a core symptom. Furthermore, elevated whole-blood 5-HT has also been described in patients with pediatric obsessive-compulsive disorder. The 5-HT1B receptor is associated with repetitive behaviors seen in both disorders. Chronic blockade of serotonin transporter (SERT) reduces 5-HT1B receptor levels in the orbitofrontal cortex (OFC) and attenuates the sensorimotor deficits and hyperactivity seen with the 5-HT1B agonist RU24969. We hypothesized that enhanced SERT function would increase 5-HT1B receptor levels in OFC and enhance sensorimotor deficits and hyperactivity induced by RU24969.ObjectivesWe examined the impact of the SERT Ala56 mutation, which leads to enhanced SERT function, on 5-HT1B receptor binding and 5-HT1B-mediated sensorimotor deficits.MethodsSpecific binding to 5-HT1B receptors was measured in OFC and striatum of naïve SERT Ala56 or wild-type mice. The impact of the 5-HT1A/1B receptor agonist RU24969 on prepulse inhibition (PPI) of startle, hyperactivity, and expression of cFos was examined.ResultsWhile enhanced SERT function increased 5-HT1B receptor levels in OFC of Ala56 mice, RU24969-induced PPI deficits and hyperlocomotion were not different between genotypes. Baseline levels of cFos expression were not different between groups. RU24969 increased cFos expression in OFC of wild-types and decreased cFos in the striatum.ConclusionsWhile reducing 5-HT1B receptors may attenuate sensorimotor gating deficits, increased 5-HT1B levels in SERT Ala56 mice do not necessarily exacerbate these deficits, potentially due to compensations during neural circuit development in this model system.

| S-EPMC8728944 | biostudies-literature

Serotonin 5-HT2A receptor activity mediates adipocyte differentiation through control of adipogenic gene expression.

Project description:Serotonin 5-HT2 receptors are expressed in many tissues and play important roles in biological processes. Although the 5-HT2A receptor is primarily known for its role in central nervous system, it is also expressed in peripheral tissues. We have found that 5-HT2A receptor antagonists inhibit human subcutaneous primary adipocyte differentiation. We also show that siRNA knockdown of the 5-HT2A receptor blocks differentiation. Using gene expression analysis in combination with receptor antagonists we found that activity of 5-HT2A receptors is necessary very early in the differentiation process to mediate expression of adipogenic genes, including peroxisome proliferator-activated receptor gamma (ppar-γ), adipocyte protein 2 (aP2), adiponectin, and serine/threonine-protein kinase 1 (sgk1). We show here for the first time that 5-HT2A receptor activity is necessary for differentiation of human primary subcutaneous preadipocytes to adipocytes, and that 5-HT2A receptor activity mediates key genes related to adipogenesis during this process. Importantly, this work contributes to a greater understanding of the adipocyte differentiation process, as well as to the role of 5-HT2A receptors in peripheral tissues, and may be relevant to the development of novel therapeutic strategies targeting this receptor for the treatment of obesity related diseases.

| S-EPMC8492876 | biostudies-literature

Development of 2-Aminotetralin-Type Serotonin 5-HT1 Agonists: Molecular Determinants for Selective Binding and Signaling at 5-HT1A, 5-HT1B, 5-HT1D, and 5-HT1F Receptors.

Project description:The serotonin (5-hydroxytryptamine, 5-HT) 5-HT1 G-protein coupled receptor subtypes (5-HT1A/1B/1D/1E/1F) share a high sequence homology, confounding development of subtype-specific ligands. This study used a 5-HT1 structure-based ligand design approach to develop subtype-selective ligands using a 5-substituted-2-aminotetralin (5-SAT) chemotype, leveraging results from pharmacological, molecular modeling, and mutagenesis studies to delineate molecular determinants for 5-SAT binding and function at 5-HT1 subtypes. 5-SATs demonstrated high affinity (Ki ≤ 25 nM) and at least 50-fold stereoselective preference ([2S] > [2R]) at 5-HT1A, 5-HT1B, and 5-HT1D receptors but essentially nil affinity (Ki > 1 μM) at 5-HT1F receptors. The 5-SATs tested were agonists with varying degrees of potency and efficacy, depending on chemotype substitution and 5-HT1 receptor subtype. Models were built from the 5-HT1A (cryo-EM), 5-HT1B (crystal), and 5-HT1D (cryo-EM) structures, and 5-SATs underwent docking studies with up to 1 μs molecular dynamics simulations. 5-SAT interactions observed at positions 3.33, 5.38, 5.42, 5.43, and 7.39 of 5-HT1 subtypes were confirmed with point mutation experiments. Additional 5-SATs were designed and synthesized to exploit experimental and computational results, yielding a new full efficacy 5-HT1A agonist with 100-fold selectivity over 5-HT1B/1D receptors. The results presented lay the foundation for the development of additional 5-HT1 subtype selective ligands for drug discovery purposes.

| S-EPMC10797628 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data