Concanavalin A-induced liver cell damage: activation of intracellular pathways triggered by tumor necrosis factor in mice.
OBJECTIVE
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.
Trautwein
C
C
Department of Gastroenterology and Hepatology, Medizinische Hochschule Hannover, Hannover, Germany.
Rakemann
T
T
Brenner
D A
DA
Streetz
K
K
Licato
L
L
Manns
M P
MP
Tiegs
G
G
D000818:Animals; D017209:Apoptosis; D001692:Biological Transport / Q000502:physiology; D002467:Cell Nucleus / Q000378:metabolism; D003208:Concanavalin A / Q000494:pharmacology*; D004247:DNA / Q000378:metabolism; D004789:Enzyme Activation / Q000502:physiology; D007425:Intracellular Membranes / Q000187:drug effects* / Q000378:metabolism*; D048031:JNK Mitogen-Activated Protein Kinases; D008099:Liver / Q000187:drug effects* / Q000473:pathology*; D008213:Lymphocyte Activation / Q000502:physiology; D048670:MAP Kinase Kinase 4; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D020929:Mitogen-Activated Protein Kinase Kinases; D016328:NF-kappa B / Q000378:metabolism; D011494:Protein Kinases / Q000378:metabolism; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism; D013601:T-Lymphocytes / Q000502:physiology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D016328:NF-kappa B; D016755:Proto-Oncogene Proteins c-jun; D014409:Tumor Necrosis Factor-alpha; D003208:Concanavalin A; D004247:DNA; D011494:Protein Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D020929:Mitogen-Activated Protein Kinase Kinases