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Altered localization and activity of canalicular Mrp2 in estradiol‐17β‐ D ‐glucuronide–induced cholestasis
Author(s) -
Mottino Aldo D.,
Cao Jingsong,
Veggi Luis M.,
Crocenzi Fernando,
Roma Marcelo G.,
Vore Mary
Publication year - 2002
Publication title -
hepatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.488
H-Index - 361
eISSN - 1527-3350
pISSN - 0270-9139
DOI - 10.1053/jhep.2002.33327
Subject(s) - multidrug resistance associated protein 2 , cholestasis , endocytic cycle , medicine , endocrinology , intracellular , internalization , excretion , chemistry , glucuronide , bone canaliculus , metabolite , biology , biochemistry , endocytosis , transporter , receptor , atp binding cassette transporter , gene
Estradiol‐17β‐ D ‐glucuronide (E 2 17G), an endogenous metabolite of estradiol, induces a potent dose‐dependent and reversible inhibition of bile flow in the rat. We analyzed the effect of a single dose of E 2 17G (15 μmol/kg, intravenously) to female rats on bile flow and the endocytic retrieval and function of the canalicular multidrug resistance‐associated protein 2 (Mrp2) and the effect of pretreatment with dibutyryl‐cyclic AMP (DBcAMP; 20 μmol/kg) on these measures. Bile flow was maximally inhibited by 85% within 10 minutes of E 2 17G and returned to 50% and 100% of control levels within 75 and 120 minutes, respectively. Western analysis of total homogenates and mixed plasma and intracellular membranes suggested partial internalization of Mrp2 during the acute phase of cholestasis at 20 minutes and during the period of recovery from cholestasis at 75 minutes, which returned to control levels by 180 minutes after E 2 17G. Confocal analysis confirmed Western studies and demonstrated endocytic retrieval of Mrp2 from the canalicular membrane into pericanalicular and intracellular domains. The biliary concentration and excretion of the model Mrp2 substrate, dinitrophenyl‐S‐glutathione (DNP‐SG), was impaired in parallel with the extent of Mrp2 retrieval. Pretreatment with DBcAMP partially protected against maximal E 2 17G cholestasis and the endocytic retrieval and decreased function of Mrp2 at 20 minutes and significantly accelerated the exocytic insertion of Mrp2 into the canalicular membrane and the recovery of bile flow and biliary excretion of DNP‐SG. In conclusion, these data indicate that E 2 17G induces endocytic internalization of Mrp2, which occurs in parallel with decreased bile flow and Mrp2 transport activity.