Taste sensing and gut feeling: Possible involvement of taste receptor type 1 family in seabream Sparus aurata.

Abstract

Taste perception of sweet and umami stimuli in vertebrates is largely controlled by a family of G-protein-coupled receptors, the taste receptor type 1 (T1R) family, with three members that combine in heterodimers to form the taste receptors. The mammalian T1R1/T1R3 receptor responds to umami compounds such as amino acids, whereas T1R2/T1R3 is activated by sweet substances. In mammals, it has been well established that taste sensing in the oral cavity (taste buds) not only guides the consumption of foods, but the presence of taste receptors in specialized cells of the gastrointestinal tract (enteroendocrine cells) can also regulate digestive, absorptive and metabolic functions through gut sensing mechanisms (Alpers, 2010; Depoortere, 2014). In fish, however, very little information is available, particularly in species of aquaculture interest. We have previously cloned the full-length cDNA of five T1R genes in Sparus aurata (sa), including the specific heterodimer subunit of the umami taste (saT1R1), three novel sweet taste duplicate genes (saT1R2x, saT1R2y, saT1R2z) and the saT1R3 gene common to both umami and sweet taste heterodimers. The objective of this study was to further characterize their functional properties and patterns of expression in both larval and adult seabream tissues.