INVESTIGADORES
SANCHEZ POZZI Enrique Juan
artículos
Título:
Ca2+-dependent protein Kinase C isoforms are critical to estradiol 17ß-D-glucuronide-induced cholestasis in the rat
Autor/es:
CROCENZI, FERNANDO A; SANCHEZ POZZI, EJ; RUIZ, M LAURA; ZUCCHETTI, AE; ROMA, MARCELO G; MOTTINO, ALDO D; VORE, MARY
Revista:
HEPATOLOGY (BALTIMORE, MD.)
Editorial:
JOHN WILEY & SONS INC
Referencias:
Año: 2008 vol. 48 p. 1885 - 1895
ISSN:
0270-9139
Resumen:
The endogenous
estradiol metabolite estradiol 17beta-D-glucuronide (E(2)17G) induces an
acute cholestasis in rat liver coincident with retrieval of the
canalicular transporters bile salt export pump (Bsep, Abcc11) and
multidrug resistance-associated protein 2 (Mrp2, Abcc2) and their
associated loss of function. We assessed the participation of
Ca(2+)-dependent protein kinase C isoforms (cPKC) in the cholestatic
manifestations of E(2)17G in perfused rat liver (PRL) and in isolated
rat hepatocyte couplets (IRHCs). In PRL, E(2)17G (2 mumol/liver;
intraportal, single injection) maximally decreased bile flow, total
glutathione, and [(3)H] taurocholate excretion by 61%, 62%, and 79%,
respectively; incorporation of the specific cPKC inhibitor Gö6976 (500
nM) in the perfusate almost totally prevented these decreases. In
dose-response studies using IRHC, E(2)17G (3.75-800 muM) decreased the
canalicular vacuolar accumulation of the Bsep substrate
cholyl-lysylfluorescein with an IC50 of 54.9 +/- 7.9 muM. Gö6976 (1 muM)
increased the IC50 to 178.4 +/- 23.1 muM, and similarly prevented the
decrease in the canalicular vacuolar accumulation of the Mrp2 substrate,
glutathione methylfluorescein. Prevention of these changes by Gö6976
coincided with complete protection against E(2)17G-induced retrieval of
Bsep and Mrp2 from the canalicular membrane, as detected both in the PRL
and IRHC. E(2)17G also increased paracellular permeability in IRHC,
which was only partially prevented by Gö6976. The cPKC isoform PKCalpha,
but not the Ca(2+)-independent PKC isoform, PKCepsilon, translocated to
the plasma membrane after E(2)17G administration in primary cultured
rat hepatocytes; Gö6976 completely prevented this translocation, thus
indicating specific activation of cPKC. This is consistent with
increased autophosphorylation of cPKC by E(2)17G, as detected via
western blotting.
CONCLUSION:
Our
findings support a central role for cPKC isoforms in E(2)17G-induced
cholestasis, by inducing both transporter retrieval from the canalicular
membrane and opening of the paracellular route.