ROLE OF P38 MITOGEN ACTIVATED PROTEIN KINASE (MAPK) IN TAUROLITHOCHOLATE (TLC)-IN- DUCED IMPAIRMENT OF MULTIDRUG RESISTANCE-ASSOCIATED PROTEIN 2 (MRP2) ACTIVITY

ANDERMATTEN, ROMINA B.; CIRIACI, NADIA; SCHUCK, VIRGINIA S.; RAZORI, MARIA VALERIA; BAROSSO, ISMAEL R.; SANCHEZ POZZI, ENRIQUE J.

Mar del Plata

Congreso; Reunión Anual de la SAIC; 2020

Sociedad Argentina de Investigación Clínica

TLC causes cholestasis inducing internalization of canalicular transporters, Mrp2 among them. In part, this effect is due to a sequential activation of sphingosine 1-phosphate receptor 2 (S1PR2), adenylyl cyclase, PKA and PI3K, which blocks the spontaneous reinsertion of Mrp2 but does not affect its initial internalization induced by TLC. Recently, we found that p38 MAPK is also implicated in the actions of TLC on Mrp2 activity independently of S1PR2. Our aim was to evaluate the role of p38 in Mrp2 internalization using the isolated perfused rat liver model (IPRL).Methodology: In IPRL, TLC (4.5 μmol/liver) was injected in the portal vein. SB203580, p38 inhibitor (SB, 500 nM), was added to reservoir 10 min before TLC. Finally, biliary flow and dinitrophenyl-glutathione (DNPG) excretion were determined. Isolated rat hepatocytes were pretreated with S1PR2 [JTE-013 (JTE 10 μM)] and PI3K [wortmannin (W 100 nM)] inhibitors and exposed to TLC (2.5 μM). Then, cells were lysed and p38 phosphorylation was analyzed by western blot.Results: (% of control ± SEM; n=3). In IPRL, TLC decreased bile flow to a minimum at min 10 post injection (3.5±0.5a) partially recovering at min 30 (19.0±3.0a). Similarly, DNPG excretion had a minimum at min 10 (2.1±0.3a) and partially recovered at min 30 (10.6±1.2a). SB did not prevent the initial decays in bile flow (11.0±2.0a) and DNPG excretion (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 induced by TLC (227±26a) decreased by W (129±7b), whereas, JTE did not affect it (299±45a). a p