Expression and functional activity of bitter taste receptors in primary renal tubular epithelial cells and M-1 cells.

The kidney is essential in the maintenance of in vivo homeostasis by body fluid and electrolyte conservation and metabolic waste removal. Previously, we reported the expression of a novel G protein family (Tas2rs), which includes bitter taste receptors, in the kidney tubule system, including the nephrons and the collecting duct system. Bitter taste receptors could affect kidney function via Ca2+ intake. Alkaloids such as phenylthiocarbamide stimulate these receptors and cause an increase in Ca2+ intake. In this study, we determined the expression of bitter taste receptors in the immature kidney and small intestine and in primary renal epithelial cells and M-1 (collecting tubule cell line) cells, by using QPCR and immunostaining. We found no expression of bitter taste receptors in the immature kidney and small intestine several days after birth; the relative abundance of Tas2rs transcripts varied depending on the developmental stage. Tas2rs were expressed in primary renal epithelial cells and M-1 cells. The traditional Chinese medicinal plant extracts phellodendrine and coptisine caused a rapid rise in intracellular Ca2+ concentration, which was inhibited by the phospholipase C (PLC) inhibitor U-73122. Thus, phellodendrine and coptisine could change the physiological status of renal cells in vitro by mediation of bitter taste receptors in a PLC-dependent manner. Our results provide new insights on the expression and role of bitter taste receptors in renal development and function.