Bitter taste receptor mTas2r105 is expressed in small intestinal villus and crypts

The small intestine is the most important digestion and absorption organ in the body. Taste receptors and taste signal transduction cascades were detected in a variety of non-lingual tissues including testis, kidney, nasal cavity, lung, heart and gastrointestinal (GI) tract. Though the expression of bitter taste receptors and taste signal transduction cascades has been reported in the gut for a decade, the evidence revealing the expression of Tas2rs in the gut remain unbelievable. Here, the amplification of 35 bitter taste receptors from small intestine cDNA revealed that all transcripts are present in duodenum, jejunum and ileum, except Tas2r117. In addition, Tas2Rs and taste-related signaling transduction cascades are also observed in mouse small intestine including duodenum, jejunum and ileum by RT-PCR and Western Blot. On the other hand, three types of transgenic system were used to investigate the expression of the bitter taste receptor Tas2r105 in mouse intestine (Tas2r105-GFP/Cre, Tas2r105-GFP/Cre-DTA and Tas2r105-GFP/Cre-LacZ). With the bitter taste receptor mTas2r105 transgenic mice, the expression of mTas2r105 is showed in the villus and crypts of small intestine. mTas2r105 positive cells are also observed at the connective tissue of villus. DTA expression in mTas2r105 + cells completely ablate the expression of mTas2r105 in intestinal epithelia, but did not ablate mTas1r3 expression in intestine epithelia. LacZ staining further reveals that bitter taste receptor mTas2r105 is expressed in crypt base cells.