Evidence that de novo protein synthesis is dispensable for anti-apoptotic effects of NF-kappaB.
The transcription factor NF-kappaB is a positive transcription factor for a number of genes and has been recognized as an anti-apoptotic regulator. However, the mechanism by which NF-kappaB blocks apoptosis is still controversial. Here, we demonstrate the evidence that NF-kappaB could attenuate the TNF-alpha-induced apoptosis without de novo protein synthesis using human pancreatic cancer cell lines, MIA PaCa-2 and Capan-2. The TNF-alpha-induced apoptosis was blocked by IL-1beta, a potent inducer of NF-kappaB activation. This inhibitory effect of IL-1beta was evident when cells were treated with protein synthesis inhibitors such as cycloheximide (CHX). Moreover, NF-kappaB decoy oligonucleotides could not block the anti-apoptotic effect of IL-1beta at doses sufficient to block the NF-kappaB-dependent transcription induced by IL-1beta. To confirm the role of NF-kappaB in blocking apoptosis, we generated stable cell lines expressing IkappaBdeltaN, a highly stable form of IkappaBalpha, a cytoplasmic inhibitor of NF-kappaB. In these stable transfectants, the antiapoptotic effect of IL-1beta was totally abolished, indicating that the anti-apoptotic action of IL-1beta could be ascribed to the NF-kappaB action. These findings show that de novo protein synthesis is dispensable for anti-apoptotic effects of NF-kappaB and support the possibility that NF-kappaB could exert its anti-apoptotic action through protein-protein interaction.
Kajino
S
S
Department of Molecular Genetics, Nagoya City University Medical School, Nagoya, Japan.
Suganuma
M
M
Teranishi
F
F
Takahashi
N
N
Tetsuka
T
T
Ohara
H
H
Itoh
M
M
Okamoto
T
T
D017209:Apoptosis / Q000187:drug effects*; D003513:Cycloheximide / Q000494:pharmacology; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004347:Drug Interactions; D006801:Humans; D020672:I-kappa B Proteins; D007375:Interleukin-1 / Q000494:pharmacology*; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000378:metabolism*; D010190:Pancreatic Neoplasms; D014176:Protein Biosynthesis; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D004268:DNA-Binding Proteins; D020672:I-kappa B Proteins; D007375:Interleukin-1; D016328:NF-kappa B; C000606204:NFKBIA protein, human; D011500:Protein Synthesis Inhibitors; D014409:Tumor Necrosis Factor-alpha; D000072000:NF-KappaB Inhibitor alpha; D003513:Cycloheximide