TNF alpha-induced hepatocyte apoptosis is associated with alterations of the cell cycle and decreased stem loop binding protein.
BACKGROUND
Inhibition of nuclear factor kappa B (NF kappa B) during liver regeneration induces hepatocyte apoptosis associated with normal DNA synthesis but decreased mitosis, suggesting that inhibition of NF kappa B impairs progression from S-phase through the G(2)/M phase of the cell cycle. Our aim was to determine if inhibition of NF kappa B alters cell cycle characteristics in hepatocytes treated with tumor necrosis factor alpha (TNF alpha).


METHODS
Primary hepatocytes from BALB/c mice were infected with adenoviruses expressing luciferase (control; AdLuc) or the I kappa B super-repressor (AdI kappa B) and treated with or without TNF alpha (30 ng/ml). Flow cytometry was performed (0 to 40 hours) to determine apoptosis and cell cycle progression. Reverse transcriptase-polymerase chain reaction and immunoblots assessed changes in cell cycle mediators and antiapoptotic factors.


RESULTS
Primary hepatocytes treated with AdI kappa B and TNF alpha demonstrated significantly more S-phase cells (14% +/- 3% vs 6% +/- 2%, P<.05) at 14 hours compared with controls. Inhibition of NF kappa B with or without TNFalpha was associated with decreased expression of stem loop bind protein, a marker of cell cycle progression through S-phase. The NF kappa B-induced antiapoptotic proteins, iNOS and TRAF2, had decreased message at 9 and 12 hours, respectively, in TNF alpha- and AdI kappa B-treated cells.


CONCLUSIONS
Inhibition of NF kappa B in TNF alpha-treated primary mouse hepatocytes is associated with increased S-phase cell cycle retention and decreased stem loop bind protein.
Black
Dalliah
D
Department of Surgery, University of North Carolina at Chapel Hill, 27599, USA.
Bird
Mark A
MA
Hayden
Melissa
M
Schrum
Laura W
LW
Lange
Patricia
P
Samson
Charles
C
Hatano
Etsuro
E
Rippe
Richard A
RA
Brenner
David A
DA
Behrns
Kevin E
KE
D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D002453:Cell Cycle / Q000187:drug effects*; D004247:DNA / Q000378:metabolism; D022781:Hepatocytes / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D020672:I-kappa B Proteins / Q000494:pharmacology; D051379:Mice; D008807:Mice, Inbred BALB C; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000235:genetics; D052247:Nitric Oxide Synthase Type II; D009687:Nuclear Proteins / Q000378:metabolism*; D011506:Proteins / Q000235:genetics; D012333:RNA, Messenger / Q000037:antagonists & inhibitors; D016601:RNA-Binding Proteins; D016196:S Phase; D047992:TNF Receptor-Associated Factor 2; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D039221:mRNA Cleavage and Polyadenylation Factors / Q000378:metabolism*
D020672:I-kappa B Proteins; D016328:NF-kappa B; D009687:Nuclear Proteins; D011506:Proteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; C490494:Slbp protein, mouse; D047992:TNF Receptor-Associated Factor 2; D014409:Tumor Necrosis Factor-alpha; D039221:mRNA Cleavage and Polyadenylation Factors; D004247:DNA; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse