Drug- and estrogen-induced cholestasis through inhibition of the hepatocellular bile salt export pump (Bsep) of rat liver.
OBJECTIVE
Drug-induced cholestasis is a frequent form of acquired liver disease. To elucidate the molecular pathogenesis of drug-induced cholestasis, we investigated the effects of prototypic cholestatic drugs on the canalicular bile salt export pump (Bsep) of rat liver.


METHODS
Vesicles were isolated from Bsep-, Mrp2-, and Bsep/Mrp2-expressing Sf9 cells. Canalicular plasma membrane (cLPM) vesicles from rat liver and Sf9 cell vesicles were used to study adenosine triphosphate (ATP)-dependent solute uptake by a rapid filtration technique.


RESULTS
Bsep-expressing Sf9 cell vesicles showed ATP-dependent transport of numerous monoanionic bile salts with similar Michaelis constant values as in cLPM vesicles, whereas several known substrates of the multispecific organic anion transporter Mrp2 were not transported by Bsep. Cyclosporin A, rifamycin SV, rifampicin, and glibenclamide cis-inhibited Bsep-mediated bile salt transport to similar extents as ATP-dependent taurocholate transport in cLPM vesicles. In contrast, the cholestatic estrogen metabolite estradiol-17beta-glucuronide inhibited ATP-dependent taurocholate transport only in normal cLPM and in Bsep/Mrp2-coexpressing Sf9 cell vesicles, but not in Mrp2-deficient cLPM or in selectively Bsep-expressing Sf9 cell vesicles, indicating that it trans-inhibits Bsep only after its secretion into bile canaliculi by Mrp2.


CONCLUSIONS
These results provide a molecular basis for previous in vivo observations and identify Bsep as an important target for induction of drug- and estrogen-induced cholestasis in mammalian liver.
Stieger
B
B
Division of Clinical Pharmacology and Toxicology, Department of Medicine, University Hospital, Zurich, Switzerland.
Fattinger
K
K
Madon
J
J
Kullak-Ublick
G A
GA
Meier
P J
PJ
D000074020:ATP Binding Cassette Transporter, Subfamily B, Member 11; D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000502:physiology*; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D027321:Anion Transport Proteins; D001647:Bile Acids and Salts / Q000378:metabolism*; D001692:Biological Transport / Q000187:drug effects; D002352:Carrier Proteins / Q000235:genetics / Q000502:physiology*; D002460:Cell Line; D016572:Cyclosporine / Q000494:pharmacology; D004958:Estradiol / Q000031:analogs & derivatives / Q000494:pharmacology; D005905:Glyburide / Q000494:pharmacology; D007700:Kinetics; D008099:Liver / Q000502:physiology*; D051381:Rats; D011994:Recombinant Proteins / Q000378:metabolism; D012293:Rifampin / Q000494:pharmacology; D012294:Rifamycins / Q000494:pharmacology; D018411:Spodoptera; D013656:Taurocholic Acid / Q000378:metabolism; D014162:Transfection
D000074020:ATP Binding Cassette Transporter, Subfamily B, Member 11; D018528:ATP-Binding Cassette Transporters; C490548:Abcb11 protein, rat; D027321:Anion Transport Proteins; D001647:Bile Acids and Salts; D002352:Carrier Proteins; D011994:Recombinant Proteins; D012294:Rifamycins; C025483:estradiol-17 beta-glucuronide; D004958:Estradiol; D013656:Taurocholic Acid; D016572:Cyclosporine; D000255:Adenosine Triphosphate; C023808:rifamycin SV; D005905:Glyburide; D012293:Rifampin