ORCID Profile
0000-0002-6606-888X
Current Organisation
University of Nottingham
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Publisher: Springer Science and Business Media LLC
Date: 02-10-2017
DOI: 10.1038/S41467-017-00716-Z
Abstract: Atypical antipsychotic drugs (APDs) have been hypothesized to show reduced extrapyramidal side effects (EPS) due to their rapid dissociation from the dopamine D 2 receptor. However, support for this hypothesis is limited to a relatively small number of observations made across several decades and under different experimental conditions. Here we show that association rates, but not dissociation rates, correlate with EPS. We measured the kinetic binding properties of a series of typical and atypical APDs in a novel time-resolved fluorescence resonance energy transfer assay, and correlated these properties with their EPS and prolactin-elevating liabilities at therapeutic doses. EPS are robustly predicted by a rebinding model that considers the microenvironment of postsynaptic D 2 receptors and integrates association and dissociation rates to calculate the net rate of reversal of receptor blockade. Thus, optimizing binding kinetics at the D 2 receptor may result in APDs with improved therapeutic profile.
Publisher: Cold Spring Harbor Laboratory
Date: 29-06-2020
DOI: 10.1101/2020.06.29.171512
Abstract: The β2-adrenoceptor (β2AR) is a well-established target in asthma and a prototypical GPCR for biophysical studies. Solubilisation of membrane proteins has classically involved the use of detergents. However, the detergent environment differs from the native membrane environment and often destabilises membrane proteins. Use of hiphilic copolymers is a promising strategy to solubilise membrane proteins within their native lipid environment in the complete absence of detergents. Here we show the isolation of the β 2 AR in the polymer Diisobutylene maleic acid (DIBMA). We demonstrate that β 2 AR remains functional in the DIBMA lipid particle (DIBMALP) and shows improved thermal stability compared to the n-Dodecyl-β-D-Maltopyranoside (DDM) detergent solubilised β 2 AR. This unique method of extracting β 2 AR offers significant advantages over previous methods routinely employed such as the introduction of thermostabilising mutations and the use of detergents, particularly for functional biophysical studies.
Publisher: American Society for Pharmacology & Experimental Therapeutics (ASPET)
Date: 25-02-2016
Abstract: Here we describe the pharmacologic properties of a series of clinically relevant chemoattractant receptor-homologous molecules expressed on T-helper type 2 (CRTh2) receptor antagonists, including fevipiprant (NVP-QAW039 or QAW039), which is currently in development for the treatment of allergic diseases. [(3)H]-QAW039 displayed high affinity for the human CRTh2 receptor (1.14 ± 0.44 nM) expressed in Chinese hamster ovary cells, the binding being reversible and competitive with the native agonist prostaglandin D2(PGD2). The binding kinetics of QAW039 determined directly using [(3)H]-QAW039 revealed mean kinetic on (kon) and off (koff) values for QAW039 of 4.5 × 10(7)M(-1)min(-1)and 0.048 minute(-1), respectively. Importantly, thekoffof QAW039 (half-life = 14.4 minutes) was >7-fold slower than the slowest reference compound tested, AZD-1981. In functional studies, QAW039 behaved as an insurmountable antagonist of PGD2-stimulated [(35)S]-GTPγS activation, and its effects were not fully reversed by increasing concentrations of PGD2after an initial 15-minute incubation period. This behavior is consistent with its relatively slow dissociation from the human CRTh2 receptor. In contrast for the other ligands tested this time-dependent effect on maximal stimulation was fully reversed by the 15-minute time point, whereas QAW039's effects persisted for >180 minutes. All CRTh2 antagonists tested inhibited PGD2-stimulated human eosinophil shape change, but importantly QAW039 retained its potency in the whole-blood shape-change assay relative to the isolated shape change assay, potentially reflective of its relatively slower off rate from the CRTh2 receptor. QAW039 was also a potent inhibitor of PGD2-induced cytokine release in human Th2 cells. Slow CRTh2 antagonist dissociation could provide increased receptor coverage in the face of pathologic PGD2concentrations, which may be clinically relevant.
Publisher: Wiley
Date: 25-09-2012
Publisher: American Chemical Society (ACS)
Date: 03-10-2019
DOI: 10.1021/ACS.JMEDCHEM.9B00864
Abstract: Haloperidol is a typical antipsychotic drug (APD) associated with an increased risk of extrapyramidal side effects (EPSs) and hyperprolactinemia relative to atypical APDs such as clozapine. Both drugs are dopamine D
Publisher: Cold Spring Harbor Laboratory
Date: 06-08-2020
DOI: 10.1101/2020.08.05.237982
Abstract: Measurements of membrane protein thermostability allows indirect detection of ligand binding. Current thermostability assays require protein purification or rely on pre-existing radiolabelled or fluorescent ligands, limiting their application to established target proteins. Alternative methods detect protein aggregation which requires sufficiently high level of protein expression. Here, we present a ThermoBRET method to quantify the relative thermostability of G protein coupled receptors (GPCRs), using cannabinoid receptors (CB 1 and CB 2 ) and the β 2 -adrenoceptor (β 2 AR) as model systems. ThermoBRET reports receptor unfolding, does not need labelled ligands and can be used with non-purified proteins. It uses Bioluminescence Resonance Energy Transfer (BRET) between Nanoluciferase (Nluc) and a thiol-reactive fluorescent dye that binds cysteines exposed by unfolding. We demonstrate that the melting point (T m ) of Nluc-fused GPCRs can be determined in non-purified detergent solubilised membrane preparations or solubilised whole cells, revealing differences in thermostability for different solubilising conditions and in the presence of stabilising ligands. We extended the range of the assay by developing the thermostable tsNLuc by incorporating mutations from the fragments of split-Nluc ( T m of 87 ⁰C vs 59 ⁰C). ThermoBRET allows determination of GPCR thermostability, which is useful for protein purification optimisation and as part of drug discovery screening strategies.
Publisher: Cold Spring Harbor Laboratory
Date: 08-07-2020
DOI: 10.1101/2020.07.07.191957
Abstract: Sensitive protein stability assays for membrane proteins are crucial for developing purification protocols, for structural and biophysical characterisation and drug discovery. Here, we describe a novel high-throughput 384-well FRET-based thermostability methodology, ThermoFRET, allowing for the ultrasensitive determination of G protein coupled receptor (GPCR) stability. This method measures FRET between a terbium-cryptate labelled GPCR and BODIPY-FL-Cystine, a thiolreactive dye that reacts with cysteine residues exposed upon protein unfolding in response to thermal denaturation. ThermoFRET is functional in crude solubilised membrane preparations, without protein purification and can detect receptor stabilising ligands, making it ideally suited for orphan receptor screening.
Publisher: American Chemical Society (ACS)
Date: 27-04-2017
Publisher: Springer Science and Business Media LLC
Date: 24-02-2016
DOI: 10.1038/NCOMMS10842
Abstract: Biased agonism describes the ability of ligands to stabilize different conformations of a GPCR linked to distinct functional outcomes and offers the prospect of designing pathway-specific drugs that avoid on-target side effects. This mechanism is usually inferred from pharmacological data with the assumption that the confounding influences of observational (that is, assay dependent) and system (that is, cell background dependent) bias are excluded by experimental design and analysis. Here we reveal that ‘kinetic context’, as determined by ligand-binding kinetics and the temporal pattern of receptor-signalling processes, can have a profound influence on the apparent bias of a series of agonists for the dopamine D 2 receptor and can even lead to reversals in the direction of bias. We propose that kinetic context must be acknowledged in the design and interpretation of studies of biased agonism.
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for David Sykes.