Han X, Budreau A M, Chesney R W
Department of Pediatrics, University of Tennessee and the Crippled Children's Foundation Research Center at Le Bonheur Children's Medical Center, Memphis 38103, USA.
Biochim Biophys Acta. 1997 Apr 10;1351(3):296-304. doi: 10.1016/s0167-4781(96)00217-5.
NaCl-dependent taurine transporter (pNCT) activity of MDCK cells (Madin-Darby canine kidney) is up- or down-regulated by medium taurine manipulation. In this study we found that the abundance of pNCT mRNA was up- or down-regulated after cells were incubated in media containing 0 microM taurine or 500 microM taurine for 24 h. Down-regulation was observed after 12 h exposure to high taurine (500 microM) and mRNA abundance was appreciably reduced after 72 h exposure. Nuclear run-off assays show that the gene for pNCT is induced at the transcriptional level by taurine. Addition of cycloheximide blocked the adaptive response and reduced transcription of pNCT mRNA in MDCK cells. Cycloheximide had virtually no effect on pNCT mRNA stability, suggesting that ongoing protein synthesis is required for adaptive regulation of pNCT gene transcription.
MDCK细胞（麦迪逊-达比犬肾细胞）的NaCl依赖性牛磺酸转运体（pNCT）活性可通过培养基中牛磺酸的调控而升高或降低。在本研究中，我们发现，将细胞在含有0微摩尔牛磺酸或500微摩尔牛磺酸的培养基中孵育24小时后，pNCT mRNA的丰度会升高或降低。在暴露于高浓度牛磺酸（500微摩尔）12小时后观察到下调，暴露72小时后mRNA丰度明显降低。细胞核转录实验表明，牛磺酸在转录水平上诱导pNCT基因。加入放线菌酮可阻断适应性反应并降低MDCK细胞中pNCT mRNA的转录。放线菌酮对pNCT mRNA稳定性几乎没有影响，这表明持续的蛋白质合成是pNCT基因转录适应性调节所必需的。
