G-protein-coupled receptors at a glance

[No abstract available

Caveolin-1 interacts with 5-HT2A serotonin receptors and profoundly modulates the signaling of selected Gαq-coupled protein receptors

5-Hydroxytryptamine 2A (5-HT2A) serotonin receptors are important for a variety of functions including vascular smooth muscle contraction, platelet aggregation, and the modulation of perception, cognition, and emotion. In a search for 5-HT2A receptor-interacting proteins, we discovered that caveolin-1 (Cav-1), a scaffolding protein enriched in caveolae, complexes with 5-HT2A receptors in a number of cell types including C6 glioma cells, transfected HEK-293 cells, and rat brain synaptic membrane preparations. To address the functional significance of this interaction, we performed RNA interference-mediated knockdown of Cav-1 in C6 glioma cells, a cell type that endogenously expresses both 5-HT2A receptors and Cav-1. We discovered that the in vitro knockdown of Cav-1 in C6 glioma cells nearly abolished 5-HT2A receptor-mediated signal transduction as measured by calcium flux assays. RNA interference-mediated knockdown of Cav-1 also greatly attenuated endogenous Gαq-coupled P2Y purinergic receptor-mediated signaling without altering the signaling of PAR-1 thrombin receptors. Cav-1 appeared to modulate 5-HT2A signaling by facilitating the interaction of 5-HT2A receptors with Gαq. These studies provide compelling evidence for a prominent role of Cav-1 in regulating the functional activity of not only 5-HT 2A serotonin receptors but also selected Gαq-coupled receptors

Discovery and Development of a Potent and Highly Selective Small Molecule Muscarinic Acetylcholine Receptor Subtype I (mAChR 1 or M-1) Antagonist In Vitro and In Vivo Probe

This article describes the discovery and development of the first highly selective, small molecule antagonist of the muscarinic acetylcholine receptor subtype I (mAChR1 or M(1)). An M(1) functional, cell-based calcium-mobilization assay identified three distinct chemical series with initial selectivity for M(1) versus M(4). An iterative parallel synthesis approach was employed to optimize all three series in parallel, which led to the development of novel microwave-assisted chemistry and provided important take home lessons for probe development projects. Ultimately, this effort produced VU0255035, a potent (IC(50) = 130 nM) and selective (>75-fold vs. M(2)-M(5) and > 10 μM vs. a panel of 75 GPCRs, ion channels and transporters) small molecule M(1) antagonist. Further profiling demonstrated that VU0255035 was centrally penetrant (Brain(AUC)/Plasma(AUC) of 0.48) and active in vivo, rendering it acceptable as both an in vitro and in vivo MLSCN/ MLPCN probe molecule for studying and dissecting M(1) function