Ischemia/reperfusion injury in the liver of BALB/c mice activates AP-1 and nuclear factor kappaB independently of IkappaB degradation.
For many inherited and acquired hepatic diseases, liver transplantation is the only possible therapeutic strategy. Ischemia/reperfusion (I/R) damage to donor tissue is thought to be one component that may play a role in the decline of posttransplant tissue function and ultimately rejection. The transcription factors, AP-1 and nuclear factor kappaB (NF-kappaB), play important roles in the acute cellular responses to tissue damage, as well as the inflammatory phase following I/R. We have found that the DNA binding activity of AP-1 was dramatically increased following warm ischemia at 1 to 3 hours postreperfusion. Induced DNA binding activity was composed of predominately c-Jun and JunD hetero- and homodimers as determined by electrophoretic mobility supershift assays. This increase in AP-1 activity occurred in the absence of significant changes in the steady-state protein levels of c-Jun and JunB. Maximal activation of Jun amino-terminal kinase ( JNK) occurred within the 25 to 30 minutes postreperfusion, just before the peak in AP-1 DNA binding. These findings suggest that phosphorylation may play an important role in regulating AP-1 transcriptional complexes. Furthermore, JunD protein levels slightly increased at 3 hours postreperfusion, concordant with changes in AP-1 DNA binding activity. The activation of NF-kappaB at 1 hour postreperfusion was independent of proteolytic degradation of IkappaB- or IkappaB-beta. This activation of NF-kappaB DNA binding activity in the nucleus was preceded by an increase in tyrosine phosphorylation of IkappaB-. These studies suggest that JNK, IkappaB tyrosine kinase, and JunD are potential targets for therapeutic intervention during liver I/R injury.
Zwacka
R M
RM
University of Iowa, Department of Anatomy and Cell Biology, Iowa City, IA, USA.
Zhang
Y
Y
Zhou
W
W
Halldorson
J
J
Engelhardt
J F
JF
D000818:Animals; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D019281:Dimerization; D004789:Enzyme Activation; D020672:I-kappa B Proteins; D007511:Ischemia / Q000378:metabolism / Q000473:pathology; D048031:JNK Mitogen-Activated Protein Kinases; D008099:Liver / Q000098:blood supply / Q000378:metabolism* / Q000473:pathology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D020928:Mitogen-Activated Protein Kinases; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000378:metabolism*; D016755:Proto-Oncogene Proteins c-jun / Q000096:biosynthesis; D015427:Reperfusion Injury / Q000378:metabolism* / Q000473:pathology; D013997:Time Factors; D018808:Transcription Factor AP-1 / Q000378:metabolism*
D004268:DNA-Binding Proteins; D020672:I-kappa B Proteins; D016328:NF-kappa B; C000606205:Nfkbia protein, mouse; D016755:Proto-Oncogene Proteins c-jun; D018808:Transcription Factor AP-1; D000072000:NF-KappaB Inhibitor alpha; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases