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

BOAGLIO, AC; ZUCCHETTI, AE; TOLEDO, FD; BAROSSO, IR; SANCHEZ POZZI EJ; CROCENZI, FA; ROMA, MG

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 to bile formation,Bsep and Mrp2. We evaluated here whether MAPKs are involved in this effect.Design: ERK1/2, JNK1/2, and p38 MAPK activation was assessed by the increase in theirphosphorylation status. Hepatocanalicular function was evaluated in isolated rat hepatocytecouplets (IRHCs) by quantifying the apical secretion of fluorescent Bsep and Mrp2substrates, and in isolated, perfused rat livers (IPRLs), using taurocholate and 2,4-dinitrophenyl-S-glutathione, respectively. Protein kinase participation in E217G-inducedsecretory failure was assessed by co-administering selective inhibitors. Internalization ofBsep/Mrp2 was assessed by confocal microscopy and image 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. The p38inhibitor 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 flow andbiliary excretion of Bsep/Mrp2 substrates. p38 inhibition prevented this initial decay, andthe internalization of Bsep/Mrp2. Contrarily, ERK1/2 inhibition accelerated the recovery ofbiliary secretion and the canalicular reinsertion of Bsep/Mrp2.