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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.
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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.
Authors: K Seino; Y Setoguchi; T Ogino; N Kayagaki; H Akiba; H Nakano; H Taniguchi; Y Takada; K Yuzawa; T Todoroki; Y Fukuchi; H Yagita; K Okumura; K Fukao Journal: Ann Surg Date: 2001-11 Impact factor: 12.969
Authors: Tom Luedde; Ulrike Assmus; Torsten Wüstefeld; Andreas Meyer zu Vilsendorf; Tania Roskams; Mark Schmidt-Supprian; Klaus Rajewsky; David A Brenner; Michael P Manns; Manolis Pasparakis; Christian Trautwein Journal: J Clin Invest Date: 2005-03-17 Impact factor: 14.808