GPCR Biased intracellular signaling evaluation
Small molecules modulating GPCR are able to selectively affect one signaling pathway over other for specific GPCR thereby “biasing” the signaling. The current explanation for this biased agonism is that GPCRs can adopt multiple active conformations stabilized by different molecules affecting intracellular signaling in different way. This divergent behavior brings further complexity in a Drug Discovery program and thus requires a methodology improvement for providing in vitro pharmacology and SAR optimization in fastest way. Such improvement can be achieved by a multiplexing approach enabling intracellular signaling analysis simultaneously.GPR43 (also known as FFA2), a G-protein coupled receptor, is activated by short-chain fatty acids (SCFA) including propionate and acetate and is coupled to both Gi and Gq protein. GPR43 has been investigated in models pertaining to the treatment of Type 2 Diabetes and Dyslipidemia. A synthetic, small-molecule Phenylacetamide (Φacetamide) has recently been published to activate GPR43 in an allosteric manner and to induce an inhibition of lipolysis through a Gi intracellular coupling. These data indicate that GPR43 agonists may have an important therapeutic role in the management of type II diabetes, dyslipidemia and aspects of the metabolic syndrome.
We present here the development of a 384-well plate multiplexed assay using both Aequorin and HTRF™ cAMP for the evaluation of Gi- and Gq-coupling in response to SCFA and Φacetamide as well as identification of biased small molecule agonists.