Murashita Koji, Yoshiura Yasutoshi, Chisada Shin-Ichi, Furuita Hirofumi, Sugita Tsuyoshi, Matsunari Hiroyuki, Iwashita Yasuro, Yamamoto Takeshi
Aquaculture Systems Division, National Research Institute of Aquaculture, Fisheries Research Agency, Tamaki, Mie, 519-0423, Japan,
Fish Physiol Biochem. 2014 Apr;40(2):511-25. doi: 10.1007/s10695-013-9862-y. Epub 2013 Sep 12.
Bile acid transporters belonging to the SLC10A protein family, Na+ taurocholate cotransporting polypeptide (NTCP or SLC10A1), apical sodium-dependent bile salt transporter (ASBT or SLC10A2), and organic solute transporter alpha (Ost-alpha) have been known to play critical roles in the enterohepatic circulation of bile acids in mammals. In this study, ntcp, asbt, and ost-alpha-1/-2 cDNA were cloned, their tissue distributions were characterized, and the effects of fasting and bile acid administration on their expression were examined in rainbow trout Oncorhynchus mykiss. The structural characteristics of Ntcp, Asbt, and Ost-alpha were well conserved in trout, and three-dimensional structure analysis showed that Ntcp and Asbt were similar to each other. Tissue distribution analysis revealed that trout asbt was primarily expressed in the hindgut, while ntcp expression occurred in the brain, and ost-alpha-1/-2 was mainly expressed in the liver or ovary. Although asbt and ost-alpha-1 mRNA levels in the gut increased in response to fasting for 4 days, ost-alpha-1 expression in the liver decreased. Similarly, bile acid administration increased asbt and ost-alpha-1 expression levels in the gut, while those of ntcp and ost-alpha-2 in the liver decreased. These results suggested that the genes asbt, ntcp, and ost-alpha are involved in bile acid transport in rainbow trout.
属于SLC10A蛋白家族的胆汁酸转运体，即牛磺胆酸钠共转运多肽（NTCP或SLC10A1）、顶端钠依赖性胆汁盐转运体（ASBT或SLC10A2）以及有机溶质转运体α（Ost-α），在哺乳动物胆汁酸的肠肝循环中发挥着关键作用。在本研究中，克隆了ntcp、asbt和ost-α-1/-2的cDNA，对它们的组织分布进行了表征，并检测了禁食和胆汁酸给药对虹鳟鱼（Oncorhynchus mykiss）中它们表达的影响。Ntcp、Asbt和Ost-α的结构特征在鳟鱼中得到了很好的保守，三维结构分析表明Ntcp和Asbt彼此相似。组织分布分析显示，虹鳟鱼的asbt主要在后肠表达，而ntcp在脑中表达，ost-α-1/-2主要在肝脏或卵巢中表达。尽管禁食4天会使肠道中asbt和ost-α-1的mRNA水平升高，但肝脏中ost-α-1的表达却下降了。同样，给予胆汁酸会增加肠道中asbt和ost-α-1的表达水平，而肝脏中ntcp和ost-α-2的表达水平则下降。这些结果表明，asbt、ntcp和ost-α基因参与了虹鳟鱼的胆汁酸转运。
