Expression of TAS2R14 in the intestinal endocrine cells of non-human primates.

BACKGROUND: Recent studies have demonstrated that genes related to bitter taste receptors (TAS2Rs) on various chromosomes are expressed in extra-oral organs of various animals. The bitter taste receptor TAS2R14 is conserved among primate species and shows broad ligand sensitivity. Mice have a number of orthologues to primate TAS2R14 located in tandem on chromosome 16; however, their expression patterns are not unique. OBJECTIVE: We characterized the expression of TAS2R14 in various cell types in the intestines of the rhesus macaque and evaluated its role in hormone production in the gut. METHODS: TAS2R14 expression was examined in the intestines of rhesus macaques, a common non-human primate model, by RT-qPCR and immunohistochemical staining. RESULTS: Mean expression levels of TAS2R14 in the duodenum, ileum, and colon were similar to each other and were lower than those in circumvallate papillae. An immunohistochemical analysis revealed TAS2R14 immunoreactivity in enteroendocrine cells positive for cholecystokinin, serotonin, and the G protein GNAT3. CONCLUSION: These results suggest that primate TAS2R14 is broadly expressed in the intestine, mainly in enteroendocrine cells, and promotes gut hormone secretion in response to bitter stimuli.

Expression of Bitter Taste Receptors in the Intestinal Cells of Non-Human Primates.

(1) Background: Recent studies have investigated the expression of taste-related genes in the organs of various animals, including humans; however, data for additional taxa are needed to facilitate comparative analyses within and among species. (2) Methods: We investigated the expression of taste-related genes in the intestines of rhesus macaques, the non-human primates most commonly used in experimental models. (3) Results: Based on RNAseq and qRT-PCR, genes encoding bitter taste receptors and the G-protein gustducin were expressed in the gut of rhesus macaques. RNAscope analysis showed that one of the bitter receptors, TAS2R38, was expressed in some cells in the small intestine, and immunohistochemical analysis revealed the presence of T2R38-positive cells in the villi of the intestines. (4) Conclusions: These results suggest that bitter receptors are expressed in the gut of rhesus macaques, supporting the use of macaques as a model for studies of human taste, including gut analyses.