Kinetic profiling an abundantly expressed planarian serotonergic GPCR identifies bromocriptine as a perdurant antagonist. Issue 3 (December 2016)

• Record Type: Journal Article
• Authors: Chan, John D.; Grab, Thomas; Marchant, Jonathan S.
• Is Part Of: International journal for parasitology. Volume 6:Issue 3(2016)
• Page Start: 356
• Page End: 363
• Publication Date: 2016-12
• Subjects: 5-HT -- Flatworm -- cAMP -- Ergot alkaloid -- Praziquantel; Parasitic diseases -- Chemotherapy -- Periodicals; Drug resistance -- Periodicals; 616.96061
• DOI: 10.1016/j.ijpddr.2016.06.002
• Languages: English
• ISSNs: 2211-3207

Abstract

Abstract: The diversity and uniqueness of flatworm G protein coupled receptors (GPCRs) provides impetus for identifying ligands useful as tools for studying flatworm biology, or as therapeutics for treating diseases caused by parasitic flatworm infections. To catalyse this discovery process, technologies optimized for mammalian GPCR high throughput screening need be transposed for screening flatworm GPCRs. Here, we demonstrate the utility of a genetically encoded cAMP biosensor for resolving the properties of an abundantly expressed planarian serotonergic GPCR (S7.1R). Application of this methodology resolved the real time kinetics of GPCR modulation by ligands and demonstrated a marked difference in the kinetic action of antagonists at S7.1R. Notably, bromocriptine caused a protracted inhibition of S7.1R activity in vitro and a protracted paralysis of planarian movement, replicating the effect of S7.1R in vivo RNAi. The lengthy inhibition of function caused by bromocriptine at this abundantly expressed GPCR provides a useful tool to ablate serotonergic signaling in vivo, and is a noteworthy feature for exploitation as an anthelmintic vulnerability. Graphical abstract: Highlights: Application of a real time cAMP biosensor to study a planarian serotonergic GPCR. The biosensor reveals differential kinetics of 5-HT GPCR inhibition by antagonists. Bromocriptine causes a persistent signaling inhibition and paralysis of intact worms. Bromocriptine action akin to a 'pharmacological knockout' of receptor function.