title: Mitogen-activated protein kinases are involved in hepatocanalicular dysfunction and cholestasis induced by oxidative stress.
abstract: In previous studies, we showed that the pro-oxidant model agent tert-butyl hydroperoxide (tBuOOH) induces alterations in hepatocanalicular secretory function by activating Ca2+-dependent protein kinase C isoforms (cPKC), via F-actin disorganization followed by endocytic internalization of canalicular transporters relevant to bile formation (Mrp2, Bsep). Since mitogen-activated protein kinases (MAPKs) may be downstream effectors of cPKC, we investigated here the involvement of the MAPKs of the ERK1/2, JNK1/2, and p38MAPKtypes in these deleterious effects. tBuOOH (100 µM, 15 min) increased the proportion of the active, phosphorylated forms of ERK1/2, JNK1/2, and p38MAPK, and panspecific PKC inhibition with bisindolylmaleimide-1 (100 nM) or selective cPKC inhibition with Gö6976 (1 μM) prevented the latter two events. In isolated rat hepatocyte couplets, tBuOOH (100 µM, 15 min) decreased the canalicular vacuolar accumulation of the fluorescent Bsep and Mrp2 substrates, cholylglycylamido fluorescein, and glutathione-methylfluorescein, respectively, and selective inhibitors of ERK1/2 (PD098059), JNK1/2 (SP600125), and p38MAPK(SB203580) partially prevented these alterations. In in situ perfused rat livers, these three MAPK inhibitors prevented tBuOOH (75 µM)-induced impairment of bile flow and the decrease in the biliary output of the Bsep and Mrp2 substrates, taurocholate, and dinitrophenyl-S-glutathione, respectively. The changes in Bsep/Mrp2 and F-actin localization induced by tBuOOH, as assessed by (immuno)fluorescence staining followed by analysis of confocal images, were prevented total or partially by the MAPK inhibitors. We concluded that MAPKs of the ERK1/2, JNK1/2, and p38MAPKtypes are all involved in cholestasis induced by oxidative stress, by promoting F-actin rearrangement and further endocytic internalization of canalicular transporters critical for bile formation.
authors.affiliation: Instituto de Fisiología Experimental (IFISE-CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (UNR), Suipacha 570, 2000, Rosario, Argentina.
authors.forename: Flavia D
authors.initials: FD
authors.lastname: Toledo
authors.affiliation: Instituto de Fisiología Experimental (IFISE-CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (UNR), Suipacha 570, 2000, Rosario, Argentina.
authors.forename: Cecilia L
authors.initials: CL
authors.lastname: Basiglio
authors.affiliation: Instituto de Fisiología Experimental (IFISE-CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (UNR), Suipacha 570, 2000, Rosario, Argentina.
authors.forename: Ismael R
authors.initials: IR
authors.lastname: Barosso
authors.affiliation: Instituto de Fisiología Experimental (IFISE-CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (UNR), Suipacha 570, 2000, Rosario, Argentina.
authors.forename: Andrea C
authors.initials: AC
authors.lastname: Boaglio
authors.affiliation: Instituto de Fisiología Experimental (IFISE-CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (UNR), Suipacha 570, 2000, Rosario, Argentina.
authors.forename: Andrés E
authors.initials: AE
authors.lastname: Zucchetti
authors.affiliation: Instituto de Fisiología Experimental (IFISE-CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (UNR), Suipacha 570, 2000, Rosario, Argentina.
authors.forename: Enrique J
authors.initials: EJ
authors.lastname: Sánchez Pozzi
authors.affiliation: Instituto de Fisiología Experimental (IFISE-CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (UNR), Suipacha 570, 2000, Rosario, Argentina. mroma@fbioyf.unr.edu.ar.
authors.forename: Marcelo G
authors.initials: MG
authors.lastname: Roma
mesh_terms: D000818:Animals; D001648:Bile Canaliculi / Q000187:drug effects* / Q000378:metabolism / Q000503:physiopathology; D002779:Cholestasis / Q000139:chemically induced* / Q000378:metabolism; D008099:Liver / Q000187:drug effects* / Q000378:metabolism / Q000503:physiopathology; D008297:Male; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D018384:Oxidative Stress / Q000187:drug effects*; D011493:Protein Kinase C / Q000378:metabolism; D017208:Rats, Wistar; D020122:tert-Butylhydroperoxide / Q000633:toxicity*
chemical_list: D020122:tert-Butylhydroperoxide; D011493:Protein Kinase C; D020928:Mitogen-Activated Protein Kinases
keywords: Actin cytoskeleton; Canalicular transporters; Hepatocellular cholestasis; Mitogen-activated protein kinases; Oxidative stress