Open AccessMechanism of inhibition of taurolithocholate‐induced retrieval of plasma membrane MRP 2 by cyclic AMP and tauroursodeoxycholate
Author(s) -
Park Se Won,
Webster Cynthia R. L.,
Anwer Mohammed S.
Publication year - 2017
Publication title -
physiological reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.918
H-Index - 39
ISSN - 2051-817X
DOI - 10.14814/phy2.13529
Subject(s) - marcks , phosphorylation , protein kinase c , microbiology and biotechnology , multidrug resistance associated protein 2 , myristoylation , chemistry , biology , biochemistry , transporter , atp binding cassette transporter , gene
Abstract Taurolithocholate ( TLC ) produces cholestasis by inhibiting biliary solute secretion in part by retrieving MRP 2 from the plasma membrane ( PM ). Tauroursodeoxycholate ( TUDC ) and cAMP reverse TLC ‐induced cholestasis by inhibiting TLC ‐induced retrieval of MRP 2. However, cellular mechanisms for this reversal are incompletely understood. Recently, we reported that TLC decreases PM ‐ MRP 2 by activating PKC ε followed by phosphorylation of myristoylated alanine‐rich C kinase substrate ( MARCKS ). Thus, cAMP and TUDC may reverse TLC ‐induced cholestasis by inhibiting the TLC / PKC ε / MARCKS phosphorylation pathway. We tested this hypothesis by determining whether TUDC and/or cAMP inhibit TLC ‐induced activation of PKC ε and phosphorylation of MARCKS . Studies were conducted in HuH‐ NTCP cell line and rat hepatocytes. Activation of PKC ε was determined from the translocation of PKC ε to PM using a biotinylation method. Phosphorylation of MARCKS was determined by immunoblotting with a phospho‐ MARCKS antibody. TLC , but not cAMP and TUDC , activated PKC ε and increased MARCKS phosphorylation in HuH‐ NTCP as well in rat hepatocytes. Treatment with TUDC or cAMP inhibited TLC ‐induced activation of PKC ε and increases in MARCKS phosphorylation in both cell types. Based on these results, we conclude that the reversal of TLC ‐induced cholestasis by cAMP and TUDC involves, at least in part, inhibition of TLC ‐mediated activation of the PKC ε/ MARCKS phosphorylation pathway.