Role of p38 mitogen activated protein kinase (MAPK) in taurolithocholate (TLC)-induced impairment of multidrug resistance-associated protein 2 (Mrp2) activity.

CIRIACI, N; BAROSSO, IR; SCHUCK, VS; SÁNCHEZ POZZI, EJ; ANDERMATTEN, RB; RAZORI, V

Buenos Aires

Congreso; LXV Reunión Anual de la Sociedad Argentina de Investigación Clínica. SAIC; 2020

TLC causes cholestasis inducing internalization of canalicular transporters,Mrp2 among them. In part, this effect is due to a sequentialactivation of sphingosine 1-phosphate receptor 2 (S1PR2), adenylylcyclase, PKA and PI3K, which blocks the spontaneous reinsertionof Mrp2 but does not affect its initial internalization induced by TLC.Recently, we found that p38 MAPK is also implicated in the actionsof TLC on Mrp2 activity independently of S1PR2. Our aim was toevaluate the role of p38 in Mrp2 internalization using the isolatedperfused rat liver model (IPRL).Methodology: In IPRL, TLC (4.5 μmol/liver) was injected in theportal vein. SB203580, p38 inhibitor (SB, 500 nM), was added toreservoir 10 min before TLC. Finally, biliary flow and dinitrophenyl-glutathione (DNPG) excretion were determined. Isolated rat hepatocyteswere pretreated with S1PR2 [JTE-013 (JTE 10 μM)] andPI3K [wortmannin (W 100 nM)] inhibitors and exposed to TLC (2.5μM). Then, cells were lysed and p38 phosphorylation was analyzedby western blot.Results: (% of control ± SEM; n=3). In IPRL, TLC decreased bile flowto a minimum at min 10 post injection (3.5±0.5a) partially recoveringat min 30 (19.0±3.0a). Similarly, DNPG excretion had a minimum atmin 10 (2.1±0.3a) and partially recovered at min 30 (10.6±1.2a). SBdid not prevent the initial decays in bile flow (11.0±2.0a) and DNPGexcretion (7.2±2.2a) but significantly improves recovery at min 30(bile flow: 40.6±5.4a,b; DNPG exc.: 25.0±5.9a,b). Activation of p38 inducedby TLC (227±26a) decreased by W (129±7b), whereas, JTEdid not affect it (299±45a). ap