| First Author | Webster CR | Year | 2014 |
| Journal | Am J Physiol Gastrointest Liver Physiol | Volume | 307 |
| Issue | 12 | Pages | G1207-15 |
| PubMed ID | 25359536 | Mgi Jnum | J:227807 |
| Mgi Id | MGI:5702827 | Doi | 10.1152/ajpgi.00165.2014 |
| Citation | Webster CR, et al. (2014) Protein kinase Cdelta protects against bile acid apoptosis by suppressing proapoptotic JNK and BIM pathways in human and rat hepatocytes. Am J Physiol Gastrointest Liver Physiol 307(12):G1207-15 |
| abstractText | Retained bile acids, which are capable of inducing cell death, activate protein kinase Cdelta (PKC-delta) in hepatocytes. In nonhepatic cells, both pro- and antiapoptotic effects of PKC-delta are described. The aim of this study was to determine the role of PKC-delta in glycochenodeoxycholate (GCDC)-induced apoptosis in rat hepatocytes and human HUH7-Na-taurocholate-cotransporting polypeptide (Ntcp) cells. Apoptosis was monitored morphologically by Hoechst staining and biochemically by immunoblotting for caspase 3 cleavage. The role of PKC-delta was evaluated with a PKC activator (phorbol myristate acetate, PMA) and PKC inhibitors (chelerythrine, H-7, or calphostin), PKC-delta knockdown, and wild-type (WT) or constitutively active (CA) PKC-delta. PKC-delta activation was monitored by immunoblotting for PKC-delta Thr505 and Tyr311 phosphorylation or by membrane translocation. JNK and Akt phosphorylation and the amount of total bisindolylmaleimide (BIM) were determined by immunoblotting. GCDC induced the translocation of PKC-delta to the mitochondria and/or plasma membrane in rat hepatocytes and HUH7-Ntcp cells and increased PKC-delta phosphorylation on Thr505, but not on Tyr311, in HUH7-Ntcp cells. GCDC-induced apoptosis was attenuated by PMA and augmented by PKC inhibition in rat hepatocytes. In HUH-Ntcp cells, transfection with CA or WT PKC-delta attenuated GCDC-induced apoptosis, whereas knockdown of PKC-delta increased GCDC-induced apoptosis. PKC-delta silencing increased GCDC-induced JNK phosphorylation, decreased GCDC-induced Akt phosphorylation, and increased expression of BIM. GCDC translocated BIM to the mitochondria in rat hepatocytes, and knockdown of BIM in HUH7-Ntcp cells decreased GCDC-induced apoptosis. Collectively, these results suggest that PKC-delta does not mediate GCDC-induced apoptosis in hepatocytes. Instead PKC-delta activation by GCDC stimulates a cytoprotective pathway that involves JNK inhibition, Akt activation, and downregulation of BIM. |
