TAUROURSODEOXYCHOLATE PREVENTS ENDOCYTIC INTERNALIZATION AND FURTHER PROTEASOMAL DEGRADATION OF THE CANALICULAR TRANSPORTER MRP2 IN ESTRADIOL 17Β-D-GLUCURONIDE-INDUCED CHOLESTASIS

MEDEOT ANABELA CAROLINA; HILLOTE GERALDINE LUCIA; SALAS GIMENA; FAZZI AGUSTINA; ROMA MARCELO GABRIEL; CROCENZI FERNANDO ARIEL

BUENOS AIRES

Congreso; CONGRESO ANUAL DE FISIOLOGIA; 2023

SAFIS

TAUROURSODEOXYCHOLATE PREVENTS ENDOCYTIC INTERNALIZATION AND FURTHER PROTEASOMAL DEGRADATION OF THE CANALICULAR TRANSPORTER MRP2 IN ESTRADIOL 17Β-D-GLUCURONIDE-INDUCED CHOLESTASISMedeot AC1, Salas GL1, Hillotte G1, Fazzi A1, Litta AA1, Crocenzi FA1, Roma MG11. Instituto de Fisiología Experimental (IFISE), UNR, CONICETIntroduction: We have shown (Hepatology 35:1409, 2002) that exacerbated endocytosis of the canalicular transporter Mrp2 is involved in cholestasis induced by estradiol 17β-D-glucuronide (E217G), a causal agent of intrahepatic cholestasis of pregnancy (ICP). It has been suggested, but not probed, that Mrp2 sustained endocytosis leads to its exacerbated degradation. Ursodeoxycholic acid (UDCA) is the first-line therapy for ICP, but its therapeutic mechanims are unknown. However, UDCA anti-endocytic properties are likely, since we have shown this effects in sepsis-induced cholestasis (Biochem Pharmacol 168:48, 2019).Objectives: To ascertain whether E217G-induced Mrp2 endocytosis leads to its accelerated proteosomal degradation, and whether tauroursodeoxycholate (TUDC), the main UDCA metabolite, can prevents this phenomenon by halting endocytosis and further degradation of Mrp2 in sandwich-cultured rat hepatocytes (SCRH).Methods: Cycloheximide (1.5 mg/ml)-treated SCRH were preincubated with the proteosomal inhibitor MG132 (10 µM, 30 min) or TUDC (100 µM, 30min), and then exposed to E217G (200 µM, 24h), or its vehicle (DMSO) in controls (C). Protein expression of Mrp2 was assessed by Western blot, its localization by immunostaining followed by confocal microscopy, and its transport function by quantifying the initial transport rate (ITR) of its fluorescent substrate GSH-S-methylfluorescein (GS-MF).Results: (*p