title: Multidrug resistance associated protein 1 protects against bilirubin-induced cytotoxicity.
abstract: We have shown that multidrug resistance associated protein 1 (MRP1) mediates ATP-dependent extrusion of bilirubin, possibly limiting its potentially toxic accumulation in cells. To determine directly if Mrp1 protects cells against unconjugated bilirubin (UCB) toxicity, mouse embryo fibroblasts (MEF) were isolated from Mrp1 knockout (-/-) mice and their wild type (WT) (+/+) littermates. Compared to WT cells, cultured MEF (-/-) cells exposed to 40-140 nM unbound [H3]-bilirubin accumulated twice as much [H3]-bilirubin (P<0.01). This was associated with greater, dose-related cytotoxicity, assessed by the methylthiazoletetrazolium test, lactate dehydrogenase release and cellular ATP content. The data confirm that Mrp1 limits intracellular accumulation of UCB and thus decreases its cytotoxicity.
authors.affiliation: Centro Studi Fegato, Bld Q, AREA Science Park, Basovizza Campus, ss 14 Km 163.5, 34012 Trieste, Italy.
authors.forename: Sebastián
authors.initials: S
authors.lastname: Calligaris
authors.forename: Dean
authors.initials: D
authors.lastname: Cekic
authors.forename: Leslye
authors.initials: L
authors.lastname: Roca-Burgos
authors.forename: Fabio
authors.initials: F
authors.lastname: Gerin
authors.forename: Graciela
authors.initials: G
authors.lastname: Mazzone
authors.forename: J Donald
authors.initials: JD
authors.lastname: Ostrow
authors.forename: Claudio
authors.initials: C
authors.lastname: Tiribelli
mesh_terms: D000255:Adenosine Triphosphate / Q000032:analysis; D000818:Animals; D001663:Bilirubin / Q000493:pharmacokinetics / Q000494:pharmacology*; D002470:Cell Survival / Q000187:drug effects*; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D005347:Fibroblasts / Q000166:cytology; D051379:Mice; D018345:Mice, Knockout; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000172:deficiency / Q000502:physiology*; D014316:Tritium
chemical_list: D000255:Adenosine Triphosphate; D001663:Bilirubin; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D014316:Tritium; C421109:multidrug resistance-associated protein 1