Expression of Bitter Taste Receptors of the T2R Family in the Gastrointestinal Tract and Enteroendocrine STC-1 Cells

• Published in: Proceedings of the National Academy of Sciences - PNAS 2002-02, Vol.99 (4), p.2392-2397
• Main Authors: Wu, S. Vincent, Rozengurt, Nora, Yang, Moon, Young, Steven H., Sinnett-Smith, James, Rozengurt, Enrique
• Format: Article
• Language: English
• Subjects: 6-n-^APropyl-2-thiouracil; 6-n-^APropylthiouracil; 6-n-Propylthiouracil; Anatomy & physiology; Animals; Biological Sciences; Blotting, Western; Calcium - metabolism; Cell Line; Cell lines; Cells; Chemoreceptor Cells - chemistry; Chemoreceptor Cells - physiology; Cloning, Molecular; Complementary DNA; denatonium; Digestive system; Digestive System - metabolism; DNA, Complementary - metabolism; Endocrine cells; Endocrine System - metabolism; Enteroendocrine cells; Epithelial cells; Gastric Mucosa - metabolism; Gene Library; Gustatory perception; Immunohistochemistry; Mice; Molecular Sequence Data; Perception; phenylthiocarbamide; Rats; Receptors; Receptors, Cell Surface - biosynthesis; Receptors, G-Protein-Coupled; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger - metabolism; Sequence Analysis, DNA; Signal Transduction; Stomach; Taste; Taste - physiology; Taste Buds - chemistry; Taste Buds - physiology; Taste cells; Time Factors; Tissue Distribution
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.042617699

Although a role for the gastric and intestinal mucosa in molecular sensing has been known for decades, the initial molecular recognition events that sense the chemical composition of the luminal contents has remained elusive. Here we identified putative taste receptor gene transcripts in the gastrointestinal tract. Our results, using reverse transcriptase-PCR, demonstrate the presence of transcripts corresponding to multiple members of the T2R family of bitter taste receptors in the antral and fundic gastric mucosa as well as in the lining of the duodenum. In addition, cDNA clones of T2R receptors were detected in a rat gastric endocrine cell cDNA library, suggesting that these receptors are expressed, at least partly, in enteroendocrine cells. Accordingly, expression of multiple T2R receptors also was found in STC-1 cells, an enteroendocrine cell line. The expression of α subunits of G proteins implicated in intracellular taste signal transduction, namely Gαgust, and Gαt-2, also was demonstrated in the gastrointestinal mucosa as well as in STC-1 cells, as revealed by reverse transcriptase-PCR and DNA sequencing, immunohistochemistry, and Western blotting. Furthermore, addition of compounds widely used in bitter taste signaling (e.g., denatonium, phenylthiocarbamide, 6-n-propil-2-thiouracil, and cycloheximide) to STC-1 cells promoted a rapid increase in intracellular Ca2+concentration. These results demonstrate the expression of bitter taste receptors of the T2R family in the mouse and rat gastrointestinal tract.