ERK1/2 and p38 MAPKs ARE COMPLEMENTARILY INVOLVED IN ESTRADIOL 17ß- D-GLUCURONIDE-INDUCED CHOLESTASIS: CROSSTALK WITH cPKC AND PI3K

BOAGLIO ANDREA; ZUCCHETTI, ANDRÉS E.; TOLEDO F.D.; BAROSSO I.R.; SÁNCHEZ POZZI E.J.; CROCENZI, FERNANDO A.; ROMA, MARCELO G.

PLOS ONE

PUBLIC LIBRARY SCIENCE

Lugar: San Francisco; Año: 2012

1932-6203

Objective: The endogenous, cholestatic metabolite estradiol 17ß-D-glucuronide(E217G) induces endocytic internalization of the canalicular transporters relevant tobile formation, Bsep and Mrp2. We evaluated here whether MAPKs are involved in thiseffect.Design: ERK1/2, JNK1/2, and p38 MAPK activation was assessed by the increase intheir phosphorylation status. Hepatocanalicular function was evaluated in isolated rathepatocyte couplets (IRHCs) by quantifying the apical secretion of fluorescent Bsepand Mrp2 substrates, and in isolated, perfused rat livers (IPRLs), using taurocholateand 2,4-dinitrophenyl-S-glutathione, respectively. Protein kinase participation inE217G-induced secretory failure was assessed by co-administering selectiveinhibitors. Internalization of Bsep/Mrp2 was assessed by confocal microscopy andimage analysis.Results: E217G activated all kinds of MAPKs. The PI3K inhibitor wortmannin preventedERK1/2 activation, whereas the cPKC inhibitor Gö6976 prevented p38 activation,suggesting that ERK1/2 and p38 are downstream of PI3K and cPKC, respectively. Thep38 inhibitor SB203580 and the ERK1/2 inhibitor PD98059, but not the JNK1/2 inhibitorSP600125, partially prevented E217G-induced changes in transporter activity andlocalization in IRHCs. p38 and ERK1/2 co-inhibition resulted in additive protection,suggesting complementary involvement of these MAPKs. In IPRLs, E217G inducedendocytosis of canalicular transporters and a rapid and sustained decrease in bile flowand biliary excretion of Bsep/Mrp2 substrates. p38 inhibition prevented this initialdecay, and the internalization of Bsep/Mrp2. Contrarily, ERK1/2 inhibition acceleratedthe recovery of biliary secretion and the canalicular reinsertion of Bsep/Mrp2.Conclusions: cPKC/p38 MAPK and PI3K/ERK1/2 signalling pathways participatecomplementarily in E217G-induced cholestasis, through internalization and sustainedintracellular retention of canalicular transporters, respectively.