Molecular cloning and heterologous expression of GPR120 from the mouse taste tissue

The existence of fat taste along with the generally recognized taste modalities (sweet, bitter, umami, salty, and sour) is currently a subject of scientific debate and active research. Available data on the signaling cascade triggered by long-chain fatty acids (FAs) in the taste cell indicate its similarity to the transduction of sweet, bitter, and umami stimuli, but the initial stages of transduction of fatty stimuli remain unclear. A member of the G-protein-coupled receptor superfamily, GPR120, is considered as one of the candidates for the role of a long-chain FA receptor operating in the taste bud. At the same time, available reports implicating GPR120 in the FA perception by the peripheral taste system are highly contradictory. In order to create a platform for further study of the contribution of GPR120 to FA transduction, we cloned GPR120 from the mouse taste tissue and expressed it in HEK-293 cells. In contrast to the parental HEK-293 cells, GPR120-positive HEK-293 cells generated receptor-like Ca²⁺ transients in response to long-chain FA application, thus confirming the literature data on the coupling of the GPR120 receptor to the phosphoinositide cascade and intracellular Ca²⁺ mobilization. The HEK-293 cells expressing recombinant GPR120 receptor may present a useful cell model for screening natural and synthetic ligands of this receptor and analyzing its coupling to intracellular signaling pathways. Co-expression of GPR120 with other signaling proteins involved in the transduction of fatty stimuli in taste cells may be useful for interpreting taste cell responses to FAs.