Trautwein C, Rakemann T, Brenner D A, Streetz K, Licato L, Manns M P, Tiegs G
Department of Gastroenterology and Hepatology, Medizinische Hochschule Hannover, Hannover, Germany.
Gastroenterology. 1998 May;114(5):1035-45. doi: 10.1016/s0016-5085(98)70324-5.
BACKGROUND & AIMS: Concanavalin A (con A) induces tumor necrosis factor (TNF)-dependent hepatocyte apoptosis resembling immune-mediated fulminant hepatic failure in humans. Intracellular pathways originating at the TNF receptor are either linked to apoptosis, nuclear factor (NF)-kappaB translocation, or Jun kinase (JNK) activation. The aim of this study was to study TNF-dependent pathways after con A injection in vivo.
Con A, con A plus anti-TNF, and control buffer were injected into BALB/c mice. Immunofluorescence, Western blot, Northern blot, gel shift, Erk, and JNK activity and DNA fragmentation experiments were performed at different time points after injection.
DNA fragmentation in hepatocytes was increased 4-24 hours after con A injection. JNK was activated maximally (>20-fold) directly after con A injection, whereas binding and nuclear translocation of NF-kappaB was maximal after 4 hours. All pathways were blocked by anti-TNF. JNK activation was specific because related ERK 1 + 2 were not activated after con A. High nuclear expression of c-Jun was already evident 1 hour after con A injection; however, in contrast to JNK, anti-TNF treatment did not block c-Jun nuclear expression and DNA binding.
In the con A model, activation of TNF-dependent pathways is associated with apoptosis of hepatocytes. Their modulation in vivo may have implications to develop new therapeutic strategies to prevent apoptosis.
伴刀豆球蛋白A（Con A）可诱导肿瘤坏死因子（TNF）依赖的肝细胞凋亡，类似于人类免疫介导的暴发性肝衰竭。源自TNF受体的细胞内信号通路要么与凋亡、核因子（NF）-κB易位相关，要么与Jun激酶（JNK）激活相关。本研究的目的是在体内研究Con A注射后TNF依赖的信号通路。
将Con A、Con A加抗TNF以及对照缓冲液注射到BALB/c小鼠体内。在注射后的不同时间点进行免疫荧光、蛋白质印迹、Northern印迹、凝胶迁移、Erk和JNK活性以及DNA片段化实验。
Con A注射后4 - 24小时肝细胞中的DNA片段化增加。Con A注射后JNK立即被最大程度激活（>20倍），而NF-κB的结合和核易位在4小时后达到最大。所有信号通路均被抗TNF阻断。JNK的激活具有特异性，因为Con A注射后相关的ERK 1 + 2未被激活。Con A注射1小时后c-Jun的高核表达就已很明显；然而，与JNK不同，抗TNF治疗并未阻断c-Jun的核表达和DNA结合。
在Con A模型中，TNF依赖信号通路的激活与肝细胞凋亡相关。它们在体内的调节可能对开发预防凋亡的新治疗策略具有重要意义。
