Role of microtubules in estradiol-17beta-D-glucuronide-induced alteration of canalicular Mrp2 localization and activity.
Estradiol-17beta-D-glucuronide (E2-17G) induces a marked but reversible inhibition of bile flow in the rat together with endocytic retrieval of multidrug resistance-associated protein 2 (Mrp2) from the canalicular membrane to intracellular structures. We analyzed the effect of pretreatment (100 min) with the microtubule inhibitor colchicine or lumicholchicine, its inactive isomer (1 micromol/kg iv), on changes in bile flow and localization and function of Mrp2 induced by E2-17G (15 micromol/kg iv). Bile flow and biliary excretion of bilirubin, an endogenous Mrp2 substrate, were measured throughout, whereas Mrp2 localization was examined at 20 and 120 min after E2-17G by confocal immunofluorescence microscopy and Western analysis. Colchicine pretreatment alone did not affect bile flow or Mrp2 localization and activity over the short time scale examined (3-4 h). Administration of E2-17G to colchicine-pretreated rats induced a marked decrease (85%) in bile flow and biliary excretion of bilirubin as well as internalization of Mrp2 at 20 min. These alterations were of a similar magnitude as in rats pretreated with lumicolchicine followed by E2-17G. Bile flow and Mrp2 localization and activity were restored to control levels within 120 min of E2-17G in animals pretreated with lumicolchicine. In contrast, in colchicine-pretreated rats followed by E2-17G, bile flow and Mrp2 activity remained significantly inhibited by 60%, and confocal and Western studies revealed sustained internalization of Mrp2 120 min after E2-17G. We conclude that recovery from E2-17G cholestasis, associated with exocytic insertion of Mrp2 in the canalicular membrane, but not its initial E2-17G-induced endocytosis, is a microtubule-dependent process.
Mottino
Aldo D
AD
Graduate Center for Toxicology, University of Kentucky, Lexington, KY 40536-0305, USA.
Crocenzi
Fernando A
FA
Pozzi
Enrique J Sánchez
EJ
Veggi
Luis M
LM
Roma
Marcelo G
MG
Vore
Mary
M
D018528:ATP-Binding Cassette Transporters / Q000378:metabolism / Q000502:physiology*; D000818:Animals; D001646:Bile / Q000378:metabolism; D001648:Bile Canaliculi / Q000378:metabolism / Q000502:physiology*; D001692:Biological Transport; D002779:Cholestasis / Q000139:chemically induced / Q000378:metabolism* / Q000517:prevention & control; D003078:Colchicine / Q000494:pharmacology; D004958:Estradiol / Q000031:analogs & derivatives* / Q000494:pharmacology*; D005260:Female; D008162:Lumicolchicines / Q000494:pharmacology; D008870:Microtubules / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley
D018528:ATP-Binding Cassette Transporters; C423013:Abcc2 protein, rat; D008162:Lumicolchicines; C025483:estradiol-17 beta-glucuronide; C042109:lumicolchicine; D004958:Estradiol; D003078:Colchicine