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Prolactin Receptors in Rat Cholangiocytes: Regulation of Level and Isoform Ratio Is Sex Independent

R. L. Bogorad1*, T. Y. Ostroukhova1, A. N. Orlova1, P. M. Rubtsov2, and O. V. Smirnova1

1Faculty of Biology, Lomonosov Moscow State University, 119992 Moscow, Russia; fax: (7-495) 939-4309; E-mail: rbogorad@yahoo.com

2Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, ul. Vavilova 32, 119991 Moscow, Russia; fax: (7-495) 135-1405

* To whom correspondence should be addressed.

Received February 8, 2005; Revision received April 27, 2005
The presence of prolactin receptor and peculiarities of its isoform expression in bile duct cells (cholangiocytes) differentially isolated from rat liver under different conditions were investigated in the present study. Normal cholangiocytes express prolactin receptor at relatively low level comparable to those of some prolactin-dependent tissues. Long receptor isoform is predominant in cholangiocytes but not in hepatocytes. The prolactin receptor level increases significantly under obstructive cholestasis due to evaluation of long and appearance of short isoforms. In rat cholangiocytes, unlike other tissues, the main positive regulators of prolactin receptor expression are cholestasis-induced factors instead of sex hormone and prolactin levels. Long isoform is predominant and induced primarily by cholestasis-induced factors.
KEY WORDS: cholestasis, bile duct ligation, RT-PCR, cholangiocyte, prolactin receptor, receptor isoforms

DOI: 10.1134/S0006297906020106