Role of PI3K in estradiol 17ß-glucuronide-induced bile salt secretory failure in hepatocyte couplets

CROCENZI FA; SANCHEZ POZZI EJ; PÉREZ LM; BASIGLIO CL; OCHOA JE; PELLEGRINO JM; MOTTINO AD; ROMA MG

Estambul

Congreso; 31st FEBS Congress – Molecules in Health and Diseases; 2006

Federation of European Biochemical Societies

Phosphoinositide 3-kinase (PI3K) activation has been associated causally with biliary secretory failure in some experimental models of cholestasis. Estardiol 17β-glucuronide (E17βG) is thought to be a key etiological agent in pregnancy-induced cholestasis. We evaluated here wether PI3K is involved in the bile salt secretory dysfunction induced by this cholestatic in isolated rat hepatocyte couplets. The percentage of couplets displaying canalicular vacuolar accumulation of the fluorescent bile salt analogue, cholyllysylfluorescein (CLF), was reduced from 68±3 to 49±3, 25±1 and 15±2 by 12.5, 25 and 50 µM E17βG, respectively. Pre-treatment with the PI3K inhibitor, wortmannin (0.1 µM, 45 min), prevented this impairment, although its protective effectiveness depended on the dose of E17βG administered (+60%, +35% and +16%, respectively, reaching a plateau from 50 µM E17βG forward); this suggest that, at high E17βG doses, other pathomechanism of E17βG-induced cholestasis become predominant. Virtually, the same results were obtained when the amount of CLF accumulated in the couplet´s canalicular vacuoles was quantified by image analysis. These results suggest that E17βG-induced bile salt failure involves PI3K, and that activation of this kinase would represent a key, initial event in the development of the cholestatic injury.