Inhibition of NF-kappa B activity induces apoptosis in murine hepatocytes.
Recently we have demonstrated that inhibition of the nuclear factor (NF)-kappa B/Rel family of transcription factors induces apoptosis of B cells. Interestingly, mice lacking the relA gene encoding the p65 subunit of NF-kappa B exhibit embryonic lethality at days 15 to 16 of gestation, accompanied by massive destruction of liver via apoptosis. To determine whether p65 protein plays a direct role in hepatocyte survival, we employed a nontransformed murine hepatocyte (NMH) cell line, which maintains to a high degree the differentiated hepatocyte phenotype. Exponentially growing NMH cells were found to possess a constitutive level of functional classical (p50/p65) NF-kappa B as assayed by electrophoretic mobility shift analysis, antibody supershift, and transient transfection assays. Treatment of NMH cells with the proteasome inhibitor lactacystin, which prevents degradation of the NF-kappa B inhibitor proteins I kappa B, induced apoptosis. Direct inhibition of the endogenous NF-kappa B activity by microinjection of NMH cells with purified specific inhibitor I kappa B-alpha-glutathione-S-transferase fusion protein or an antibody against p65 protein induced apoptosis. These findings suggest that expression of NF-kappa B/Rel activity in murine hepatocytes acts directly to promote survival of these cells and suggest that apoptosis observed in hepatocytes of mice lacking relA is a direct effect of p65 deficiency.
Bellas
R E
RE
Department of Biochemistry, Boston University School of Medicine, Massachusetts 02118, USA.
FitzGerald
M J
MJ
Fausto
N
N
Sonenshein
G E
GE
D000111:Acetylcysteine / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000502:physiology; D002135:Calcium-Binding Proteins; D002460:Cell Line; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D015342:DNA Probes / Q000737:chemistry; D005982:Glutathione Transferase / Q000235:genetics / Q000494:pharmacology; D008099:Liver / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D008562:Membrane Glycoproteins / Q000502:physiology; D051379:Mice; D008845:Microinjections; D016328:NF-kappa B / Q000037:antagonists & inhibitors*; D009419:Nerve Tissue Proteins / Q000502:physiology; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000494:pharmacology*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000494:pharmacology; D050863:Synaptotagmin I; D050857:Synaptotagmins; D051841:Transcription Factor RelB; D014157:Transcription Factors
D002135:Calcium-Binding Proteins; D015853:Cysteine Proteinase Inhibitors; D015342:DNA Probes; D008562:Membrane Glycoproteins; D016328:NF-kappa B; D009419:Nerve Tissue Proteins; D011518:Proto-Oncogene Proteins; D011993:Recombinant Fusion Proteins; C497594:Relb protein, mouse; D050863:Synaptotagmin I; D014157:Transcription Factors; C067713:lactacystin; D050857:Synaptotagmins; D051841:Transcription Factor RelB; D005982:Glutathione Transferase; D000111:Acetylcysteine