Expression and localization of rat NBC4c in liver and renal uroepithelium
Expression and localization of rat NBC4c in liver and renal uroepithelium
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DOI：
10.1152/ajpcell.00590.2003
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发表时间：
2004-09-01
影响因子：
5.5
通讯作者：
Kurtz, I
中科院分区：
文献类型：
--
作者：
Abuladze, N;Pushkin, A;Kurtz, I
以前的研究提供了功能的证据，在肝细胞和肝内胆管胆管细胞的产电Na+-HCO 3-共转运。介导肝中产电性碳酸氢钠共转运的转运蛋白的分子身份目前尚不清楚。已知的产电Na+-HCO 3- cotransporters（NBC 1和NBC 4），我们以前表明，NBC 4 mRNA在肝脏中高度表达。在本研究中，我们进行了RT-PCR，免疫印迹和免疫组化的特点NBC 4在大鼠肝脏和肾脏的表达模式。为了进行免疫检测，产生针对大鼠NBC 4的多克隆抗体并进行亲和纯化。在已知的人NBC 4变异体中，只有大鼠NBC 4c的直系同源物在大鼠肝脏中被RT-PCR检测到，并且NBC 4c蛋白的分子量与145 kDa相似。NBC 4c蛋白在肝细胞和肝内胆管的胆管细胞中表达。在肝细胞中，NBC 4c定位于基底外侧质膜，而肝内胆管细胞染色顶部。NBC 1产电钠转运蛋白变异体kNBC 1和pNBC 1在大鼠肝脏中未被免疫印迹和免疫组化检测到。NBC 4c在肝脏中的定位模式表明，协同转运蛋白在介导肝细胞和肝内胆管细胞中的Na+-HCO 3-协同转运中起作用。与肝脏不同，大鼠肾脏表达产电钠-碳酸氢盐协同转运蛋白KNBC 1和NBC 4c。在肾脏中，NBC 4c也具有类似于145 kDa的分子量，并且免疫定位于肾盂衬里的尿路上皮细胞，其中协同转运蛋白可能在保护肾实质免受尿液pH改变的影响中发挥重要作用。
Previous studies provided functional evidence for electrogenic Na+-HCO3- cotransport in hepatocytes and in intrahepatic bile duct cholangiocytes. The molecular identity of the transporters mediating electrogenic sodium-bicarbonate cotransport in the liver is currently unknown. Of the known electrogenic Na+-HCO3- cotransporters (NBC1 and NBC4), we previously showed that NBC4 mRNA is highly expressed in the liver. In the present study, we performed RT-PCR, immunoblotting, and immunohistochemistry to characterize the expression pattern of NBC4 in rat liver and kidney. For immunodetection, a polyclonal antibody against rat NBC4 was generated and affinity purified. Of the known human NBC4 variants, only the rat NBC4c ortholog was detected by RT-PCR in rat liver, and the molecular mass of the NBC4c protein was similar to145 kDa. NBC4c protein was expressed in hepatocytes and in the cholangiocytes lining the intrahepatic bile ducts. In hepatocytes, NBC4c was localized to the basolateral plasma membrane, whereas intrahepatic cholangiocytes stained apically. The NBC1 electrogenic sodium cotransporter variants kNBC1 and pNBC1 were not detected by immunoblotting and immunohistochemistry in rat liver. The pattern of localization of NBC4c in the liver suggests that the cotransporter plays a role in mediating Na+-HCO3- cotransport in hepatocytes and intrahepatic cholangiocytes. Unlike the liver, the rat kidney expressed electrogenic sodium-bicarbonate cotransporter proteins kNBC1 and NBC4c. In kidney, NBC4c also had a molecular mass of similar to 145 kDa and was immunolocalized to uroepithelial cells lining the renal pelvis, where the cotransporter may play an important role in protecting the renal parenchyma from alterations in urine pH.