Fluorescent GPCR Ligands as New Tools in Pharmacology

Abstract

The expansion of fluorescent techniques for studying the ligand-receptor interaction resulted in a burst of the novel fluorescent ligands development. The discovery of the ligand, that is of high affinity to the receptor and whose localization could be easily visualized, even on the single cell level, gave the researchers a strong impulse to investigate that field of GPCR ligands. Moreover, paying attention to the "non pharmacological" advantages of these ligands, as well as the techniques to be used, fluorescent ligands are becoming treated more seriously, as the ligands themselves, and as novel, useful tools for studying GPCRs. Herein, we review results described in the literature, starting from the year 2000, in the field of the fluorescent GPCR small, non-peptide ligands according to the affinity to the selected receptors (histamine, adenosine, adrenergic, cannabinoid, muscarinie, neuropeptide Y and serotonine) as well as the fluorophores that have been used to tag the molecules.

Novel fluorescent antagonist as a molecular probe in A3 adenosine receptor binding assays using flow cytometry

“…Receptor-selective fluorescent ligands are used increasingly as tools for the study of receptor physiology and pathophysiology at the cellular and even the subcellular level [7]. Furthermore, they are being investigated as screening tools in drug discovery [6].…”

Design, synthesis and biological evaluation of fluorescent ligands for MT1and/or MT2melatonin receptors

“…For this reason, the choice of both the fluorophore and linker between the fluorophore and the pharmacophore is crucial and has to be optimized in order to hopefully keep the biological activity and allow the insertion of the ligands in the binding site of GPCRs. Our choice went to six families of fluorophores ie, nitrobenzoxadiazole (NBD), dansyl, phthalimide, BODIPY Fl®, 13 fluorescein, rhodamine which have been selected i) for their reported efficiency in GPCRs probes 14 and ii) for the complementary range of emission wavelength (from 450 to 600 nm). Most of those fluorophores are commonly coupled through an activated ester with an amine linked to the pharmacophore.…”

Contributions of fluorescence techniques to understanding G protein-coupled receptor dimerisation

“…The availability and suitability of fluorescent ligands depends on two main factors-the chemistry to manufacture them and the ability to label whilst retaining affinity and efficacy. A large number of fluorescent ligands are available for GPCRs (Kuder and Kiec-Kononowicz 2008), but there will no doubt be receptors for which production of such ligands is challenging. It should be noted that in this type of experiment it is impossible to study dimers in the unliganded state, a condition which may be of particular significance when ligand binding can promote or inhibit dimer formation (Lukasiewicz et al Pioszak et al 2010).…”