Physiological significance of taurine and the taurine transporter in intestinal epithelial cells.
Taurine transport in human intestinal epithelial Caco-2 cells was down-regulated by culturing the cells in taurine-containing media and was up-regulated in a taurine-free medium. This adaptive regulation was associated with changes in both the Vmax and Km values of taurine transport. A change in the mRNA level of the taurine transporter (TAUT) in this regulation was also observed. The presence of such a regulatory mechanism for maintaining the intracellular taurine content at a certain level suggests that taurine plays an important role in the intestinal cell functions. The intracellular taurine content was increased when Caco-2 cells were exposed to a hypertonic stress. TAUT was up-regulated via the increased expression of TAUT mRNA in the hypertonic cells, suggesting that taurine serves as an osmolyte and protects the cells from osmotic stress. Similar up-regulation of TAUT was observed in the small intestine of water-deprived rats.
Shimizu
M
M
Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Japan.
Satsu
H
H
D018938:Caco-2 Cells; D002352:Carrier Proteins / Q000502:physiology*; D006801:Humans; D007413:Intestinal Mucosa / Q000502:physiology*; D008562:Membrane Glycoproteins / Q000502:physiology*; D026901:Membrane Transport Proteins; D013654:Taurine / Q000502:physiology*; D015854:Up-Regulation; D000099247:Taurine Transporters
D002352:Carrier Proteins; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D013654:Taurine; D000099247:Taurine Transporters