SPHINGOSINE 1-PHOSPHATE RECEPTOR 2 (S1PR2) IS POTENTIALLY INVOLVED IN TAUROLITHOCHOLATE (TLC)‑INDUCED IMPAIRMENT OF MULTIDRUG RESISTANCE-ASSOCIATED PROTEIN 2 (MRP2) ACTIVITY

ANDERMATTEN, ROMINA; CIRIACI, NADIA; RAZZORI, MARIA VALERIA; BAROSSO, IR; SANCHEZ POZZI, EJ

Mar del Plata

Congreso; Reunión Anual de SAIC-SAI 2016; 2016

SAIC-SAI

TLC is a bile salt that induces internalization of the canalicular transporter Mrp2 through adenylyl cyclase (AC)/PKA and PI3Kdependent pathways. There are a few G-protein coupled receptors that interact with bile salts. Among them, S1PR2 in the only one, described up to now, that is present in hepatocytes and potentially activates adenylyl cyclase. In consequence our aim was to evaluatethe role of this receptor in the impairment of Mrp2 transport activity induced by TLC.Methodology: Isolated rat hepatocyte couplets were preincubated with the antagonist of S1PR2, JTE-013 (JTE, 10 μM) and then exposed to TLC (2.5 μM). Studies of additivity in the protection of inhibitors were carried out by coadministration of JTE with PI3K inhibitor wortmannina (W, 100 nM) before exposure to TLC. Functional changes in Mrp2 under the treatments described above were evaluated by assessing the canalicular vacuolar accumulation (cVA) of glutathione methylfluorescein (GMF), a fluorescent Mrp2 substrate derived from the addition of chloromethylfluorescein diacetate (CMFDA, 2.5 μM). Moreover, isolated hepatocytes were pretreated with JTE and exposed to TLC. Then, cells were lysed and western blot was performed for analysis of AKT phosphorylation, an indicator of AKT activation.Results: (% of control ± SEM; n=3-9). Treatment with JTE partially prevented TLC-induced impairment in Mrp2 activity: TLC (55±2a), TLC+JTE (79±2a,b). The preventive effects of W and JTE were not additive: TLC (55±2a), TLC+JTE (79±2a,b), TLC+W (77±6a,b), TLC+W+JTE (79±6a,b) suggesting that S1PR2 andPI3K share the same signaling pathway. Activation of AKT induced by TLC decreased in presence of JTE: TLC (584±23a), TLC+JTE (161±27a,b). a p