2007 Fiscal Year Final Research Report Summary
Intrahepatic imaging and molecular analysis of MRP2 localization regulated by the intracellular redox status
| Project/Area Number |
18390012
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Physical pharmacy
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| Research Institution | Chiba University |
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Principal Investigator |
HORIE Toshiharu Chiba University, Graduate school of pharmaceutical sciences, Professor (90120154)
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| Co-Investigator(Kenkyū-buntansha) |
SHITARA Yoshihisa Chiba University, Graduate school of pharmaceutical sciences, Lecturer (00306656)
SEKINE Shuichi Chiba University, Graduate school of pharmaceutical sciences, Assistant Professor (70401007)
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| Project Period (FY) |
2006 – 2007
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| Keywords | Biophysical / Signal transduction / Drug reactivity / Protein |
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| Research Abstract |
Oxidative stress is known to be a common feature of cholestatic syndrome. We have described the internalization of multidrug resistance-associated protein 2 (Mrp2), a biliary transporter involved in bile-salt independent bile flow, under acute oxidative stress and a series of signaling pathways finally leading to the activation of novel protein kinase C (nPKC) were involved in this mechanism; however, it has been unclear whether the internalized Mrp2 localization was re-localized to the canalicular membrane when the intracellular redox status was recovered from oxidative stress. In this research, we demonstrated that decreased canalicular expression of Mrp2 induced by tertiary-butyl hydroperoxide (t-BHP) was recovered to the canalicular membrane by the replenishment of GSH by GSH-ethyl ester, a cell-permeable form of GSH. Moreover, pretreatment of isolated rat hepatocytes with colchicine and protein kinase A (PKA) inhibitor did not affect the t-BHP induced Mrp2 internalization process, but did prevent the Mrp2 recycling process induced by GSH replenishment. Moreover, intracellular cAMP concentration similarly changed with the change of intracellular GSH content. Taken together, our data clearly indicate that the redox-sensitive balance of PKA/PKC activation regulates the reversible Mrp2 localization in two different pathways, the microtubule-independent internalization pathway and -dependent recycling pathway of Mrp2.
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