Modulation of protein kinase C by taurolithocholic acid in isolated rat hepatocytes

Abstract

The protein kinase C (PKC) family of isoenzymes plays a key role in the regulation of hepatocellular secretion. The hydrophobic and cholestatic bile acid, taurolithocholic acid (TLCA), acts as a potent Ca++ agonist in isolated hepatocytes. However, its effect on PKC isoforms has not been elucidated. Here we investigate the effects of TLCA at low micromolar concentrations on the distribution of PKC isoforms and on membrane-associated PKC activity. The distribution of PKC isoforms was determined in isolated rat hepatocytes in short-term culture using Western blotting and immunofluorescence techniques. PKC activity was measured radiochemically. TLCA (10 μmol/L) induced selective translocation of ε-PKC by 47.9% ± 20.5% (P < .05 vs. controls; n = 5) and 72.4% ± 37.2% (P