Graf Dirk, Reinehr Roland, Kurz Anna Kordelia, Fischer Richard, Häussinger Dieter
Department for Gastroenterology, Hepatology and Infectiology, Heinrich Heine University Düsseldorf, Moorenstrasse 5, D-40225 Düsseldorf, Germany.
Arch Biochem Biophys. 2003 Jul 1;415(1):34-42. doi: 10.1016/s0003-9861(03)00224-8.
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, 100 micromol/l) led to a sustained activation of mitogen activated protein (MAP) kinases (JNK, p38(MAPK), 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.
在培养24小时的大鼠肝细胞中研究了环磷酸腺苷（cAMP）抑制胆汁酸诱导的细胞凋亡的机制。牛磺石胆酸3 - 硫酸盐（TLCS，100微摩尔/升）导致丝裂原活化蛋白（MAP）激酶（JNK、p38（MAPK）和ERK）持续激活、蛋白激酶B（PKB）去磷酸化、半胱天冬酶3和8激活以及肝细胞凋亡。cAMP可预防TLCS诱导的细胞凋亡，将TLCS持续诱导的MAP激酶反应转变为瞬时模式，并防止PKB去磷酸化。TLCS诱导的CD95和TRAIL受体 - 2向质膜的转运受到显著抑制。蛋白激酶A（PKA）的阻断消除了cAMP对TLCS诱导的CD95膜靶向的抑制作用，但对TRAIL受体 - 2膜靶向、PKB和MAP激酶反应无影响。PKA抑制剂H89对cAMP诱导的抑制TLCS触发的聚（ADP）核糖聚合酶（PARP）裂解和半胱天冬酶激活没有影响，但消除了cAMP诱导的对TLCS触发的TUNEL和膜联蛋白V染色的抑制作用。结论是，cAMP通过PKA依赖和非依赖机制抑制胆汁酸诱导的细胞凋亡。
