ESTRADIOL 17 BETA-D-GLUCURONIDE (E17G) INDUCES SWITCH OF THE CANALICULAR TRANSPORTERS BSEP AND MRP2 FROM RAFT TO NON-RAFT MICRODOMAINS, FOLLOWED BY CLATHRIN-DEPENDENT ENDOCYTOSIS

BOAGLIO, ANDREA; ROMA, MARCELO G.; BAROSSO, ISMAEL R.; SÁNCHEZ POZZI E.J.; MISZCZUK, GISEL S.; LAROCCA, M. CECILIA; CROCENZI, FERNANDO A.

Mar del Plata

Congreso; LXI Reunión Científica Anual de la Sociedad Argentina de Investigación Clínica (SAIC); 2016

SAIC

Endocytosis of canalicular transporters is a Mey pathomechanismof E)induced cholestasis. +n preliminary experiments in rat hepatocytecouplets, Ye reported that this process is prevented by specificinhibitors of the clathrindependent endocytosis /edicina Supl.+++, , . +n physiological conditions, canalicular transportersare mostly presented in raft highcholesterol, caveolinenrichedmicrodomains. Clathrindependent endocytosis requires both thepresence of the cargo in nonraft loYcholesterol, clathrinenrichedmicrodomains and the recruitment of the adaptor protein A2 tothese domains. First, Ye evaluated Yhether E) induces a shift of$sep and /rp from raft to nonraft microdomains, in order to alloYfor clathrindependent endocytosis from the latter domain. E) zmol/g b.Y. Yas administered to Yhole rats, and liver samplesYere taMen after min, Yhen the maximum decrease of bile floYis reached. Highly purified plasma membrane fractions composedof raft or nonraft microdomains Yere obtained by ultracentrifugationfrom liver homogenates enrichment of these fractions Yas assessedby Yestern blot of the specific marMers caveolin and clathrin, respectively.9estern blot of $sep and /rp shoYed that E) induced asYitch betYeen microdomains, leading to a high enrichment of thesetransporters in the nonraft fraction $sep ` of total vs ` incontrols /rp ` of total vs ` in controls. To evaluate thedependency of A2 for E)induced canalicular transporter endocytosis,Ye performed si40A MnocMdoYn of A2 in sandYichculturedrat hepatocytes. A2 MnocMdoYn completely prevented E)inducedendocytosis of $sep and /rp, as shoYn by confocal microscopyanalysis. Thus, Ye proposed that E)induced endocytosis of$sep and /rp in rat livers involves a sYitch of these transportersfrom raft to nonraft canalicular microdomains, from Yhere they areendocytosed by a clathrindependent mechanism.