A2B adenosine receptor-triggered intracellular calcium mobilization: Cell type-dependent involvement of Gi, Gq, Gs proteins and protein kinase C.

Activation of PLCβ enzymes by G and G proteins is a common mechanism to trigger cytosolic Ca increase. We and others reported that G inhibitor FR900358 (FR) can inhibit both and G - and, surprisingly, G -mediated intracellular Ca mobilization. Thus, the G -G -PLCβ-Ca signaling axis depends entirely on the presence of active G , which reasonably explained FR-inhibited G -induced Ca release.

Photoswitchable Diazocine Derivative for Adenosine A Receptor Activation in Psoriasis.

Incorporating photoisomerizable moieties within drugs offers the possibility of rapid and reversible light-dependent switching between active and inactive configurations. Here, we developed a photoswitchable adenosine A receptor (AR) agonist that confers optical control on this G protein-coupled receptor through noninvasive topical skin irradiation in an animal model of psoriasis. This was achieved by covalently bonding an adenosine-5'-methyluronamide moiety to a diazocine photochrome, whose singular photoswitching properties facilitated repeated interconversion between a thermally stable, biologically inactive agonist form and a photoinduced, pharmacologically active configuration.

Third-Generation CD73 Inhibitors Based on a 4,6-Disubstituted-2-thiopyridine Scaffold.

Various series of 4,6-disubstituted-2-thiopyridine derivatives were synthesized and evaluated as potential ecto-5'-nucleotidase (CD73) inhibitors. Altogether, about ninety compounds were prepared using a general synthetic pathway involving one or two steps (eventually one-pot) procedures. Variation of the nature of the substituents in positions 4 and 6 (methyl, trifluoromethyl or phenyl) of the thiopurine ring, as well as on the thiol function, was examined and led to marked differences both in term of reactivity and ability to interfere with the putative target protein.

Mitochondrial A adenosine receptor as a mechanism for the protective effects of AAR agonists on chemotherapy-induced neuropathic pain.

Alterations in mitochondrial function are the linchpin in numerous disease states including in the development of chemotherapy-induced neuropathic pain (CIPN), a major dose-limiting toxicity of widely used chemotherapeutic cytotoxins. In CIPN, mitochondrial dysfunction is characterized by deficits in mitochondrial bioenergetics (e.g.

Potent and Selective Human 5-HT Serotonin Receptor Antagonists: 4'-Cyano-(N)-methanocarba-adenosines by Synthetic Serendipity.

Rigidified nucleoside derivatives with (N)-methanocarba replacement of ribose have been repurposed as peripheral subtype-selective 5-HT serotonin receptor antagonists for heart and lung fibrosis and intestinal/vascular conditions. 4'-Cyano derivative (MRS8209; , 4.27 nM) was 47-fold (human binding, but not rat and mouse) and 724-fold (functionally) selective at 5-HTR, compared to antitarget 5-HTR, and predicted to form a stable receptor complex using docking and molecular dynamics.

MRS3997, a dual adenosine A/A receptor agonist, reduces brain ischemic damage and alleviates neuroinflammation in rats.

The endogenous neuromodulator adenosine is massively released during hypoxic/ischemic insults and differentially modulates post-ischemic damage depending on the expression and recruitment of its four metabotropic receptor subtypes, namely A, A, A and A receptors (ARs, ARs, ARs and ARs). We previously demonstrated, by using a model of transient middle cerebral artery occlusion (tMCAo) in rats, that selective activation of ARs, as well as ARs, ameliorates post-ischemic brain damage in contrast to neuroinflammation. In the present study, we investigated whether the multitarget nucleoside MRS3997, a full agonist at both ARs and ARs, would afford higher neuroprotection in post-ischemic damage.

Selective bioorthogonal probe for N-glycan hybrid structures.

Metabolic incorporation of chemically tagged monosaccharides is a facile means of tagging cellular glycoproteins and glycolipids. However, since the monosaccharide precursors are often shared by several pathways, selectivity has been difficult to attain. For example, N-linked glycosylation is a chemically complex and ubiquitous posttranslational modification, with three distinct classes of GlcNAc-containing N-glycan structures: oligomannose, hybrid and complex.

Chimeras Derived from a P2Y Receptor Antagonist and UDP-Sugar Agonists for Potential Treatment of Inflammation.

Tethered glycoconjugates of a naphthalene- and piperidine-containing antagonist of the P2Y receptor (PPTN) were synthesized, and their nM receptor binding affinity was determined using a fluorescent tracer in hP2YR-expressing whole CHO cells. The rationale for preparing mono- and disaccharide conjugates of the antagonists was to explore the receptor binding site, which we know recognizes a glucose moiety on the native agonist (UDP-glucose), as well as enhance aqueous solubility and pharmacokinetics, including kidney excretion to potentially counteract sterile inflammation. Glycoconjugates with varied linker length, including PEG chains, were compared in hP2YR binding, suggesting that an optimal affinity (IC, nM) in the piperidine series was achieved for triazolyl -linked glucose conjugates having one (, MRS4872, 3.

Structure-Activity Relationship of Truncated 4'-Selenonucleosides: A Adenosine Receptor Activity and Binding Selectivity.

This study explored the impact of structural modifications on truncated 4'-selenonucleosides as ligands for the A adenosine receptor (AR). We synthesized and evaluated a series of these compounds for their binding affinities, functional activities, and structural interactions by using computational modeling. The SAR study revealed that all compounds exhibited selective and notable hAAR binding, among which ( = 5.

Functionalized Congeners of 2-Chromene P2Y Receptor Antagonists.

The P2Y receptor (P2YR), a G-coupled receptor, is a potential drug discovery target for various inflammatory and degenerative conditions. Antagonists have been shown to attenuate colitis, acute lung injury, etc. In the search for competitive antagonists, we have investigated the SAR of 3-nitro-2-(trifluoromethyl)-2-chromene derivatives, although high affinity is lacking.

Pilot-Scale Screening of Clinically Approved Drugs to Identify Uridine Insertion/Deletion RNA Editing Inhibitors in .

RNA editing pathway is a validated target in kinetoplastid parasites (, , and spp.) that cause severe diseases in humans and livestock. An essential large protein complex, the editosome, mediates uridine insertion and deletion in RNA editing through a stepwise process.

Structure of the human dopamine transporter and mechanisms of inhibition.

The neurotransmitter dopamine has central roles in mood, appetite, arousal and movement. Despite its importance in brain physiology and function, and as a target for illicit and therapeutic drugs, the human dopamine transporter (hDAT) and mechanisms by which it is inhibited by small molecules and Zn are without a high-resolution structural context. Here we determine the structure of hDAT in a tripartite complex with the competitive inhibitor and cocaine analogue, (-)-2-β-carbomethoxy-3-β-(4-fluorophenyl)tropane (β-CFT), the non-competitive inhibitor MRS7292 and Zn (ref.

2-Substituted (N)-Methanocarba A Adenosine Receptor Agonists: In Silico, In Vitro, and In Vivo Characterization.

2-Arylethynyl (N)-methanocarba adenosine 5'-methylamides are selective A adenosine receptor (AR) agonists containing a preestablished receptor-preferred pseudoribose conformation. Here, we compare analogues having bulky 2-substitution, either containing or lacking an ethynyl spacer between adenine and a cyclic group. 2-Aryl compounds -, , , , , , , , , and , lacking a spacer, had human (h) AAR values of 2-30 nM, and others displayed lower affinity.

Structural Modification and Biological Evaluation of 2,8-Disubstituted Adenine and Its Nucleosides as A Adenosine Receptor Antagonists: Exploring the Roles of Ribose at Adenosine Receptors.

Building on the preceding structural analysis and a structure-activity relationship (SAR) of 8-aryl-2-hexynyl nucleoside hAAR antagonist , we strategically inverted C2/C8 substituents and eliminated the ribose moiety. These modifications aimed to mitigate potential steric interactions between ribose and adenosine receptors. The SAR findings indicated that such inversions significantly modulated hAAR binding affinities depending on the type of ribose, whereas removal of ribose altered the functional efficacy via hAAR.

A adenosine receptor signaling and regulation.

The A adenosine receptor (AR) is one of the four adenosine-activated G protein-coupled receptors. In addition to adenosine, protein kinase C (PKC) was recently found to activate the AR. The AR is coupled to both G and G, as well as G proteins in some cell types.

Terpenes from Cannabis sativa induce antinociception in a mouse model of chronic neuropathic pain via activation of adenosine A 2A receptors.

Terpenes are small hydrocarbon compounds that impart aroma and taste to many plants, including Cannabis sativa . A number of studies have shown that terpenes can produce pain relief in various pain states in both humans and animals. However, these studies were methodologically limited and few established mechanisms of action.

Analgesic candidate adenosine A 3 receptors are expressed by perineuronal peripheral macrophages in human dorsal root ganglion and spinal cord microglia.

Adenosine receptors are a family of purinergic G protein-coupled receptors that are widely distributed in bodily organs and in the peripheral and central nervous systems. Recently, antihyperalgesic actions have been suggested for the adenosine A 3 receptor, and its agonists have been proposed as new neuropathic pain treatments. We hypothesized that these receptors may be expressed in nociceptive primary afferent neurons.

Machine learning-aided search for ligands of P2Y and other P2Y receptors.

The P2Y receptor, activated by uridine diphosphate (UDP), is a target for antagonists in inflammatory, neurodegenerative, and metabolic disorders, yet few potent and selective antagonists are known to date. This prompted us to use machine learning as a novel approach to aid ligand discovery, with pharmacological evaluation at three P2YR subtypes: initially P2Y and subsequently P2Y and P2Y. Relying on extensive published data for P2YR agonists, we generated and validated an array of classification machine learning model using the algorithms deep learning (DL), adaboost classifier (ada), Bernoulli NB (bnb), k-nearest neighbors (kNN) classifier, logistic regression (lreg), random forest classifier (rf), support vector classification (SVC), and XGBoost (XGB) classifier models, and the common consensus was applied to molecular selection of 21 diverse structures.

Genetic and functional modulation by agonist MRS5698 and allosteric enhancer LUF6000 at the native A adenosine receptor in HL-60 cells.

The A adenosine receptor (AR) is an important inflammatory and immunological target. However, the underlying mechanisms are not fully understood. Here, we report the gene regulation in HL-60 cells treated acutely with highly selective AAR agonist MRS5698, positive allosteric modulator (PAM) LUF6000, or both.

Membrane mimetic-dependence of GPCR energy landscapes.

We leveraged variable-temperature F-NMR spectroscopy to compare the conformational equilibria of the human A adenosine receptor (AAR), a class A G protein-coupled receptor (GPCR), across a range of temperatures ranging from lower temperatures typically employed in F-NMR experiments to physiological temperature. AAR complexes with partial agonists and full agonists showed large increases in the population of a fully active conformation with increasing temperature. NMR data measured at physiological temperature were more in line with functional data.

Dual /C7-Substituted 7-Deazapurine and Tricyclic Ribonucleosides with Affinity for G Protein-Coupled Receptors.

Various purine-based nucleoside analogues have demonstrated unexpected affinity for nonpurinergic G protein-coupled receptors (GPCRs), such as opioid and serotonin receptors. In this work, we synthesized a small library of new 7-deazaadenosine and pyrazolo[3,4-]pyrimidine riboside analogues, featuring dual C7 and modifications and assessed their affinity for various GPCRs. During the course of the synthesis of 7-ethynyl pyrazolo[3,4-]pyrimidine ribosides, we observed the formation of an unprecedented tricyclic nucleobase, formed via a 6- ring closure.

Extrahelical Binding Site for a 1-Imidazo[4,5-c]quinolin-4-amine A Adenosine Receptor Positive Allosteric Modulator on Helix 8 and Distal Portions of Transmembrane Domains 1 and 7.

This study describes the localization and computational prediction of a binding site for the A adenosine receptor (AAR) positive allosteric modulator 2-cyclohexyl-1-imidazo[4,5-c]quinolin-4-(3,4-dichlorophenyl)amine (LUF6000). The work reveals an extrahelical lipid-facing binding pocket disparate from the orthosteric binding site that encompasses transmembrane domain (TMD) 1, TMD7, and Helix (H) 8, which was predicted by molecular modeling and validated by mutagenesis. According to the model, the nearly planar 1-imidazo[4,5-c]quinolinamine ring system lies parallel to the transmembrane segments, inserted into an aromatic cage formed by π-π stacking interactions with the side chains of Y284 in TMD7 and Y293 in H8 and by π-NH bonding between Y284 and the exocyclic amine.