Normal liver regeneration in p50/nuclear factor kappaB1 knockout mice.
Nuclear factor kappaB (NF-kappaB) is rapidly activated during liver regeneration following partial hepatectomy or carbon tetrachloride (CCl(4))-mediated liver injury and is felt to be important in the antiapoptotic and regenerative responses. After partial hepatectomy, livers of mice deficient in the p50 subunit of NF-kappaB (p50(-/-)) showed a loss of NF-kappaB and decreased STAT3 transcription factor DNA binding activities. However, nuclear levels of the NF-kappaB p65 subunit were increased and peaked earlier in p50(-/-) livers. Both messenger RNA and cytoplasmic protein levels of the NF-kappaB inhibitor IkappaBalpha were lower in p50(-/-) livers, potentially accounting for the increase in p65 protein. Small effects on gene expression posthepatectomy were observed in p50(-/-) livers, but no effects were seen on hepatocyte DNA synthetic or mitotic responses, serum enzyme levels, or overall liver mass restoration. After CCl(4) treatment, hepatocyte DNA synthesis and mitosis and serum enzyme levels were similar in p50(-/-) and p50(+/+) mice, and histologic analysis indicated a slight decrease in overall damage in p50(-/-) livers. After injection of Fas antibody, p50(-/-) livers showed an earlier onset of nuclear changes consistent with apoptosis. These data indicate that absence of p50 affects certain protein and gene activation pathways following partial hepatectomy, CCl(4), and Fas treatment but does not impair overall liver regeneration. Interleukin 6 (IL-6) levels were reduced but still adequate to support regeneration. We hypothesize that increased levels of the NF-kappaB p65 subunit in p50(-/-) livers may provide compensation for the absence of p50, thereby allowing normal liver regeneration and repair following liver injury.
Department of Genetics, University of Pennsylvania Medical School, Philadelphia 19104, USA.
R A
RA
DeAngelis
K
K
Kovalovich
D E
DE
Cressman
R
R
Taub
D000410:Alanine Transaminase / Q000097:blood; D000818:Animals; D017209:Apoptosis; D002251:Carbon Tetrachloride / Q000494:pharmacology; D004247:DNA / Q000096:biosynthesis; D004268:DNA-Binding Proteins / Q000378:metabolism; D015870:Gene Expression; D006498:Hepatectomy / Q000379:methods; D020672:I-kappa B Proteins / Q000378:metabolism; D007274:Injections, Intraperitoneal; D008099:Liver / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D008115:Liver Regeneration / Q000502:physiology*; D051379:Mice; D018345:Mice, Knockout / Q000235:genetics; D016328:NF-kappa B / Q000235:genetics / Q000502:physiology*; D020033:Protein Isoforms / Q000235:genetics / Q000502:physiology; D012016:Reference Values; D050796:STAT3 Transcription Factor; D015534:Trans-Activators / Q000378:metabolism; D019014:fas Receptor / Q000494:pharmacology
D004268:DNA-Binding Proteins; D020672:I-kappa B Proteins; D016328:NF-kappa B; D020033:Protein Isoforms; D050796:STAT3 Transcription Factor; C494087:Stat3 protein, mouse; D015534:Trans-Activators; D019014:fas Receptor; D004247:DNA; D002251:Carbon Tetrachloride; D000410:Alanine Transaminase