Tanaka Yuji, Kobayashi Yoshinao, Gabazza Esteban C, Higuchi Kunihiro, Kamisako Toshinori, Kuroda Makoto, Takeuchi Keisuke, Iwasa Motoh, Kaito Masahiko, Adachi Yukihiko
Third Department of Internal Medicine, Mie University School of Medicine, 2 - 174 Edobashi, Tsu City, 514 - 8507, Japan.
Am J Physiol Gastrointest Liver Physiol. 2002 Apr;282(4):G656-62. doi: 10.1152/ajpgi.00383.2001.
Regulation of bilirubin glucuronide transporters during hyperbilirubinemia in hepatic and extrahepatic tissues is not completely clear. In the present study, we evaluated the regulation of the bilirubin glucuronide transporters, multidrug resistance-associated proteins (MRP)2 and 3, in rats with obstructive jaundice. Bile duct ligation (BDL) or sham operation was performed in Wistar rats. Liver and kidneys were removed 1, 3, and 5 days after BDL (n = 4, in each group). Serum and urine were collected to measure bilirubin levels just before animal killing. MRP2 And MRP3 mRNA expressions were determined by real-time RT-PCR. Protein expression of MRP2 and MRP3 was determined by Western blotting. Renal MRP2 function was evaluated by para-aminohippurate (PAH) clearance. The effect of conjugated bilirubin, unconjugated bilirubin, human bile, and sulfate-conjugated bile acid on MRP2 gene expression was also evaluated in renal and hepatocyte cell lines. Serum bilirubin and urinary bilirubin excretion increased significantly after BDL. In the liver, the mRNA expression of MRP2 decreased 59, 86, and 82%, and its protein expression decreased 25, 74, and 93% compared with sham-operated animals after 24, 72, and 120 h of BDL, respectively. In contrast, the liver expression of MRP3 mRNA increased 138, 2,137, and 3,295%, and its protein expression increased 560, 634, and 612% compared with sham-operated animals after 24, 72, and 120 h of BDL, respectively. On the other hand, in the kidneys, the mRNA expression of MRP2 increased 162, 73, and 21%, and its protein expression increased 387, 558, and 472% compared with sham-operated animals after 24, 72, and 120 h of BDL, respectively. PAH clearance was significantly increased after BDL. The mRNA expression of MRP2 increased in renal proximal tubular epithelial cells after treatment with conjugated bilirubin, sulfate-conjugated bile acid or human bile. Upregulation of MRP2 in the kidneys and MRP3 in the liver may be a compensatory mechanism to improve bilirubin clearance during obstructive jaundice.
肝组织和肝外组织在高胆红素血症期间胆红素葡萄糖醛酸转运蛋白的调节机制尚不完全清楚。在本研究中，我们评估了阻塞性黄疸大鼠中胆红素葡萄糖醛酸转运蛋白、多药耐药相关蛋白（MRP）2和3的调节情况。对Wistar大鼠进行胆管结扎（BDL）或假手术。在BDL术后1、3和5天取出肝脏和肾脏（每组n = 4）。在处死动物前收集血清和尿液以测量胆红素水平。通过实时RT-PCR测定MRP2和MRP3 mRNA表达。通过蛋白质印迹法测定MRP2和MRP3的蛋白表达。通过对氨基马尿酸（PAH）清除率评估肾脏MRP2功能。还在肾和肝细胞系中评估了结合胆红素、未结合胆红素、人胆汁和硫酸结合胆汁酸对MRP2基因表达的影响。BDL术后血清胆红素和尿胆红素排泄显著增加。在肝脏中，与假手术动物相比，BDL术后24、72和120小时，MRP2的mRNA表达分别下降了59%、86%和82%，其蛋白表达分别下降了25%、74%和93%。相反，与假手术动物相比，BDL术后24、72和120小时，肝脏中MRP3 mRNA表达分别增加了138%、2137%和3295%，其蛋白表达分别增加了560%、634%和612%。另一方面，在肾脏中，与假手术动物相比，BDL术后24、72和120小时，MRP2的mRNA表达分别增加了162%、73%和21%，其蛋白表达分别增加了387%、558%和472%。BDL术后PAH清除率显著增加。用结合胆红素、硫酸结合胆汁酸或人胆汁处理后，肾近端小管上皮细胞中MRP2的mRNA表达增加。肾脏中MRP2和肝脏中MRP3的上调可能是阻塞性黄疸期间改善胆红素清除的一种代偿机制。
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