Inhibition of taurolithocholate 3-sulfate-induced apoptosis by cyclic AMP in rat hepatocytes involves protein kinase A-dependent and -independent mechanisms
- 作者：Graf ; Dirk ; Reinehr ; Roland ; Kurz ; Anna Kordelia ; Fischer ; Richard ; Hä ; ussinger ; Dieter
- 关键词：Apoptosis ; Bile acids ; CD95 trafficking ; TRAIL-2 ; PKA/MAP kinases
- 刊名：Archives of Biochemistry and Biophysics
- 出版年：2003
- 期刊代码：116_00039861
- 类别：ch
- 出版时间：July 1, 2003
- 卷：415
- 期：1
- 页码：34-42
- 文件大小：409 K
摘要
The mechanisms underlying the inhibition of bile acid-induced apoptosis by cyclic AMP (cAMP) were studied in 24-h-cultured rat hepatocytes. Taurolithocholate 3-sulfate (TLCS, 100μmol/l) led to a sustained activation of mitogen activated protein (MAP) kinases (JNK, p38MAPK, and ERKs), dephosphorylation of protein kinase B (PKB), activation of caspases 3 and 8, and hepatocyte apoptosis. cAMP prevented TLCS-induced apoptosis, shifted the persistent TLCS-induced MAP kinase response to a transient pattern, and prevented PKB dephosphorylation. TLCS-induced CD95 and TRAIL receptor-2 trafficking to the plasma membrane were significantly inhibited. Blockade of protein kinase A (PKA) abolished the inhibitory effect of cAMP on TLCS-induced CD95 membrane targeting, but not TRAIL receptor-2 membrane targeting, PKB and MAP kinase responses. H89, an inhibitor of PKA, had no effect on cAMP-induced inhibition of TLCS-triggered poly(ADP) ribose polymerase (PARP) cleavage and caspase activation, but abolished the cAMP-induced inhibition of TLCS-triggered TUNEL- and Annexin V staining. It is concluded that cAMP inhibits bile acid-induced apoptosis via PKA-dependent and -independent mechanisms.