Interaction of Mrp2 with radixin causes reversible canalicular Mrp2 localization induced by intracellular redox status

BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR BASIS OF DISEASE

卷:1812

Article

Sekine, Shuichi¹  Ito, Kousei²  Saeki, Junjiro¹  Horie, Toshiharu¹ 

[1] Chiba Univ, Grad Sch Pharmaceut Sci, Lab Biopharmaceut, Chuo Ku, Chiba 2608675, Japan

[2] Univ Tokyo, Fac Med, Tokyo Univ Hosp, Dept Pharm,Bunkyo Ku, Tokyo 1138655, Japan

关键词: Mrp2;    Radixin;    Cholestasis;    Oxidative stress;    Internalization;   

DOI  :  10.1016/j.bbadis.2011.07.015

来源: Elsevier

【 摘 要 】

Oxidative stress is a feature of cholestatic syndrome and induces multidrug resistance-associated protein 2 (Mrp2) internalization from the canalicular membrane surface. We have previously shown that the activation of a novel protein kinase C (nPKC) by oxidative stress regulates Mrp2 internalization. The internalized Mrp2 was recycled to the canalicular surface in a protein kinase A (PKA)-dependent manner after intracellular glutathione (GSH) levels were replenished. However, the putative phosphorylation targets of these protein kinases involved in reversible Mrp2 trafficking remain unclear. In this study, we investigated the effect of changing the intrahepatic redox status on the C-terminal phosphorylation status of radixin (p-radixin), which links Mrp2 to F-actin, and the interaction of p-radixin with Mrp2 in rat hepatocytes. We detected a significant decrease in the amount of p-radixin that co-immunoprecipitated with Mrp2 after tertiary-butylhydroperoxide (t-BHP) treatment. After treatment with GSH-ethylester (GSH-EE), the phosphorylation level became the same as that of the control. A PKC and protein phosphatase (PP)-1/2A inhibitor, but not a PP-2A selective inhibitor, prevented the t-BHP-induced decrease of p-radixin and subsequent canalicular Mrp2 localization. In contrast, a PKA inhibitor affected the recovery process facilitated by GSH-EE treatment. In conclusion, the interaction of p-radixin with Mrp2 was decreased by the activation of PKC and PP-1 under oxidative stress conditions which subsequently led to Mrp2 internalization, whereas the interaction of p-radixin and Mrp2 was increased by the activation of PKA during recovery from oxidative stress. (C) 2011 Elsevier B.V. All rights reserved.

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