Retrieval of the mrp2 gene encoded conjugate export pump from the canalicular membrane contributes to cholestasis induced by tert-butyl hydroperoxide and chloro-dinitrobenzene
Retrieval of the mrp2 gene encoded conjugate export pump from the canalicular membrane contributes to cholestasis induced by tert-butyl hydroperoxide and chloro-dinitrobenzene
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DOI：
10.1515/bc.2000.063
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发表时间：
2000-05-01
影响因子：
3.7
通讯作者：
Häussinger, D
中科院分区：
文献类型：
--
作者：
Schmitt, M;Kubitz, R;Häussinger, D
已知氧化应激可诱导胆汁淤积，但对其潜在机制知之甚少。在这项研究中，我们已经表征了叔丁基过氧化氢（t-BOOH）和1-氯-2，4-二硝基苯（CDNB）对mrp 2基因编码的小管输出泵（Mrp 2）的短期影响。在灌流大鼠肝脏中研究了t-BOOH和CDNB对胆汁形成、组织GSH水平和亚细胞Mrp 2定位的影响。t-BOOH（0.5 mM）和CDNB（0.1 mM）均在60分钟内诱导肝脏GSH水平降低90%以上，胆汁流量几乎完全停止。如共聚焦激光扫描显微镜所示，这种胆汁淤积伴随着免疫反应性MRP 2从小管膜的损失及其在肝细胞内出现在推定的细胞内囊泡中。另一方面，二肽基肽酶IV（DPPIV），另一种小管蛋白，和封闭小带相关多肽（ZO-1）的细胞内分布保持不受影响，表明Mrp 2检索模式的选择性。t-BOOH和CDNB都诱导了肝脏的快速净K+流出和肝细胞水合作用的显著降低。我们的结论是，严重的谷胱甘肽耗竭诱导胆汁淤积的检索Mrp 2，但不是DPPIV从小管膜。潜在的机制尚不清楚;然而，在这些条件下发生的肝细胞水合作用的减少可能有助于这种效应。
Oxidative stress is known to induce cholestasis, but the underlying mechanisms are poorly understood. In this study we have characterized the short-term effects of tert-butyl hydroperoxide (t-BOOH)- and 1-chloro-2,4-dinitrobenzene (CDNB) on the mrp2 gene encoded canalicular export pump (Mrp2). The effects of t-BOOH and CDNB on bile formation, tissue GSH levels and subcellular Mrp2 localization were studied in perfused rat liver. Both, t-BOOH (0.5 mM) and CDNB (0.1 mM) induced within 60 min a decrease of hepatic GSH levels by more than 90% and an almost complete cessation of bile flow. As revealed by confocal laser scanning microscopy, this cholestasis was accompanied by a loss of immunoreactive MRP2 from the canalicular membrane and its appearance inside the hepatocytes in putative intracellular vesicles. On the other hand, the intracellular distribution of dipeptidyl peptidase IV (DPPIV), another canalicular protein, and of zonula occludens associated polypeptide (ZO-1) remained unaffected, indicating selectivity of the Mrp2 retrieval pattern. Both, t-BOOH and CDNB induced a rapid net K+ efflux from the liver and a significant decrease of liver cell hydration. We conclude that severe glutathione depletion induces cholestasis by a retrieval of Mrp2, but not of DPPIV from the canalicular membrane. The underlying mechanism is unclear; however, a decrease in liver cell hydration, which occurs under these conditions, may contribute to this effect.