Crystal structures of the A2A adenosine receptor and their use in medicinal chemistry.
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ABSTRACT:
SUBMITTER: Jacobson KA
PROVIDER: S-EPMC3956660 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:The A2A adenosine receptor is a protein belonging to a family of four GPCR adenosine receptors. It is involved in the regulation of several pathophysiological conditions in both the central nervous system and periphery. In the brain, its localization at pre- and postsynaptic level in striatum, cortex, hippocampus and its effects on glutamate release, microglia and astrocyte activation account for a crucial role in neurodegenerative diseases, including Alzheimer's disease (AD). This ailment is considered the main form of dementia and is expected to exponentially increase in coming years. The pathological tracts of AD include amyloid peptide-β extracellular accumulation and tau hyperphosphorylation, causing neuronal cell death, cognitive deficit, and memory loss. Interestingly, in vitro and in vivo studies have demonstrated that A2A adenosine receptor antagonists may counteract each of these clinical signs, representing an important new strategy to fight a disease for which unfortunately only symptomatic drugs are available. This review offers a brief overview of the biological effects mediated by A2A adenosine receptors in AD animal and human studies and reports the state of the art of A2A adenosine receptor antagonists currently in clinical trials. As an original approach, it focuses on the crucial role of pharmacokinetics and ability to pass the blood-brain barrier in the discovery of new agents for treating CNS disorders. Considering that A2A receptor antagonist istradefylline is already commercially available for Parkinson's disease treatment, if the proof of concept of these ligands in AD is confirmed and reinforced, it will be easier to offer a new hope for AD patients.
| S-EPMC9102440 | biostudies-literature
Project description:The G protein-coupled adenosine A2A receptor (A2A AR) is an important new (potential) drug target in immuno-oncology, and for neurodegenerative diseases. Preladenant and its derivatives belong to the most potent A2A AR antagonists displaying exceptional selectivity. While crystal structures of the human A2A AR have been solved, mostly using the A2A -StaR2 protein that bears 9 point mutations, co-crystallization with Preladenant derivatives has so far been elusive. We developed a new A2A AR construct harboring a single point mutation (S913.39 K) which renders it extremely thermostable. This allowed the co-crystallization of two novel Preladenant derivatives, the polyethylene glycol-conjugated (PEGylated) PSB-2113, and the fluorophore-labeled PSB-2115. The obtained crystal structures (2.25 Å and 2.6 Å resolution) provide explanations for the high potency and selectivity of Preladenant derivatives. They represent the first crystal structures of a GPCR in complex with PEG- and fluorophore-conjugated ligands. The applied strategy is predicted to be applicable to further class A GPCRs.
| S-EPMC9310709 | biostudies-literature
Project description:The adenosine A2A receptor (A2AR) has long been implicated in cardiovascular disorders. As more selective A2AR ligands are being identified, its roles in other disorders, such as Parkinson's disease, are starting to emerge, and A2AR antagonists are important drug candidates for nondopaminergic anti-Parkinson treatment. Here we report the crystal structure of A2A receptor bound to compound 1 (Cmpd-1), a novel A2AR/N-methyl d-aspartate receptor subtype 2B (NR2B) dual antagonist and potential anti-Parkinson candidate compound, at 3.5 Å resolution. The A2A receptor with a cytochrome b562-RIL (BRIL) fusion (A2AR-BRIL) in the intracellular loop 3 (ICL3) was crystallized in detergent micelles using vapor-phase diffusion. Whereas A2AR-BRIL bound to the antagonist ZM241385 has previously been crystallized in lipidic cubic phase (LCP), structural differences in the Cmpd-1-bound A2AR-BRIL prevented formation of the lattice observed with the ZM241385-bound receptor. The crystals grew with a type II crystal lattice in contrast to the typical type I packing seen from membrane protein structures crystallized in LCP. Cmpd-1 binds in a position that overlaps with the native ligand adenosine, but its methoxyphenyl group extends to an exosite not previously observed in other A2AR structures. Structural analysis revealed that Cmpd-1 binding results in the unique conformations of two tyrosine residues, Tyr91.35 and Tyr2717.36, which are critical for the formation of the exosite. The structure reveals insights into antagonist binding that are not observed in other A2AR structures, highlighting flexibility in the binding pocket that may facilitate the development of A2AR-selective compounds for the treatment of Parkinson's disease.
| S-EPMC5338372 | biostudies-literature
Project description:The Gs protein-coupled adenosine A2A receptor (A2AAR) represents an emerging drug target for cancer immunotherapy. The clinical candidate Etrumadenant was developed as an A2AAR antagonist with ancillary blockade of the A2BAR subtype. It constitutes a unique chemotype featuring a poly-substituted 2-amino-4-phenyl-6-triazolylpyrimidine core structure. Herein, we report two crystal structures of the A2AAR in complex with Etrumadenant, obtained with differently thermostabilized A2AAR constructs. This led to the discovery of an unprecedented interaction, a hydrogen bond of T883.36 with the cyano group of Etrumadenant. T883.36 is mutated in most A2AAR constructs used for crystallization, which has prevented the discovery of its interactions. In-vitro characterization of Etrumadenant indicated low selectivity versus the A1AR subtype, which can be rationalized by the structural data. These results will facilitate the future design of AR antagonists with desired selectivity. Moreover, they highlight the advantages of the employed A2AAR crystallization construct that is devoid of ligand binding site mutations.
| S-EPMC10235125 | biostudies-literature
Project description:The A3 adenosine receptor (A3 AR) subtype is a novel, promising therapeutic target for inflammatory diseases, such as rheumatoid arthritis (RA) and psoriasis, as well as liver cancer. A3 AR is coupled to inhibition of adenylyl cyclase and regulation of mitogen-activated protein kinase (MAPK) pathways, leading to modulation of transcription. Furthermore, A3 AR affects functions of almost all immune cells and the proliferation of cancer cells. Numerous A3 AR agonists, partial agonists, antagonists, and allosteric modulators have been reported, and their structure-activity relationships (SARs) have been studied culminating in the development of potent and selective molecules with drug-like characteristics. The efficacy of nucleoside agonists may be suppressed to produce antagonists, by structural modification of the ribose moiety. Diverse classes of heterocycles have been discovered as selective A3 AR blockers, although with large species differences. Thus, as a result of intense basic research efforts, the outlook for development of A3 AR modulators for human therapeutics is encouraging. Two prototypical selective agonists, N6-(3-Iodobenzyl)adenosine-5'-N-methyluronamide (IB-MECA; CF101) and 2-chloro-N6-(3-iodobenzyl)-adenosine-5'-N-methyluronamide (Cl-IB-MECA; CF102), have progressed to advanced clinical trials. They were found safe and well tolerated in all preclinical and human clinical studies and showed promising results, particularly in psoriasis and RA, where the A3 AR is both a promising therapeutic target and a biologically predictive marker, suggesting a personalized medicine approach. Targeting the A3 AR may pave the way for safe and efficacious treatments for patient populations affected by inflammatory diseases, cancer, and other conditions.
| S-EPMC5756520 | biostudies-literature
Project description:In this study, we determined the crystal structure of an engineered human adenosine A2A receptor bound to a partial agonist and compared it to structures cocrystallized with either a full agonist or an antagonist/inverse agonist. The interaction between the partial agonist, belonging to a class of dicyanopyridines, and amino acids in the ligand binding pocket inspired us to develop a small library of derivatives and assess their affinity in radioligand binding studies and potency and intrinsic activity in a functional, label-free, intact cell assay. It appeared that some of the derivatives retained the partial agonist profile, whereas other ligands turned into inverse agonists. We rationalized this remarkable behavior with additional computational docking studies.
| S-EPMC8154574 | biostudies-literature
Project description:The structure of the human A2A adenosine receptor has been elucidated by X-ray crystallography with a high affinity non-xanthine antagonist, ZM241385, bound to it. This template molecule served as a starting point for the incorporation of reactive moieties that cause the ligand to covalently bind to the receptor. In particular, we incorporated a fluorosulfonyl moiety onto ZM241385, which yielded LUF7445 (4-((3-((7-amino-2-(furan-2-yl)-[1, 2, 4]triazolo[1,5-a][1, 3, 5]triazin-5-yl)amino)propyl)carbamoyl)benzene sulfonyl fluoride). In a radioligand binding assay, LUF7445 acted as a potent antagonist, with an apparent affinity for the hA2A receptor in the nanomolar range. Its apparent affinity increased with longer incubation time, suggesting an increasing level of covalent binding over time. An in silico A2A-structure-based docking model was used to study the binding mode of LUF7445. This led us to perform site-directed mutagenesis of the A2A receptor to probe and validate the target lysine amino acid K153 for covalent binding. Meanwhile, a functional assay combined with wash-out experiments was set up to investigate the efficacy of covalent binding of LUF7445. All these experiments led us to conclude LUF7445 is a valuable molecular tool for further investigating covalent interactions at this receptor. It may also serve as a prototype for a therapeutic approach in which a covalent antagonist may be needed to counteract prolonged and persistent presence of the endogenous ligand adenosine.
| S-EPMC5432479 | biostudies-literature
Project description:Two 15 μs all-atom simulations of the A2A adenosine receptor were obtained in a ternary mixture of cholesterol, saturated phosphatidylcholine lipids, and unsaturated phosphatidylcholine lipids. An analysis of local lipid solvation is reported on the basis of a Voronoi tessellation of the upper and lower leaflets, identifying first and second solvation shells. The local environments of both the inactive state and the partially active state of the receptor are significantly enriched with unsaturated chains but depleted of cholesterol and saturated chains, relative to the bulk membrane composition. In spite of the local depletion of cholesterol, the partially active receptor binds cholesterol at three locations during the entire simulation trajectory. These long-lived interactions represent the extreme of a very broad distribution of first-solvation shell lipid lifetimes, confounding sharp distinctions between lipid interactions. The broad distributions of lifetimes also make equilibrating the local lipid environment difficult, necessitating long simulation times.
| S-EPMC7722239 | biostudies-literature
Project description:Using activity-based protein profiling (ABPP), functional proteins can be interrogated in their native environment. Despite their pharmaceutical relevance, G protein-coupled receptors (GPCRs) have been difficult to address through ABPP. In the current study, we took the prototypical human adenosine A2A receptor (hA2AR) as the starting point for the construction of a chemical toolbox allowing two-step affinity-based labeling of GPCRs. First, we equipped an irreversibly binding hA2AR ligand with a terminal alkyne to serve as probe. We showed that our probe irreversibly and concentration-dependently labeled purified hA2AR. Click-ligation with a sulfonated cyanine-3 fluorophore allowed us to visualize the receptor on SDS-PAGE. We further demonstrated that labeling of the purified hA2AR by our probe could be inhibited by selective antagonists. Lastly, we showed successful labeling of the receptor in cell membranes overexpressing hA2AR, making our probe a promising affinity-based tool compound that sets the stage for the further development of probes for GPCRs.
| S-EPMC6150691 | biostudies-literature
Project description:The A2A adenosine receptor (A2AAR) is one of the four subtypes activated by nucleoside adenosine, and the molecules able to selectively counteract its action are attractive tools for neurodegenerative disorders. In order to find novel A2AAR ligands, two series of compounds based on purine and triazolotriazine scaffolds were synthesized and tested at ARs. Compound 13 was also tested in an in vitro model of neuroinflammation. Some compounds were found to possess high affinity for A2AAR, and it was observed that compound 13 exerted anti-inflammatory properties in microglial cells. Molecular modeling studies results were in good agreement with the binding affinity data and underlined that triazolotriazine and purine scaffolds are interchangeable only when 5- and 2-positions of the triazolotriazine moiety (corresponding to the purine 2- and 8-positions) are substituted.
| S-EPMC9032385 | biostudies-literature