A direct requirement of nuclear factor-kappa B for suppression of apoptosis in ventricular myocytes.
Nuclear factor-kappa B (NF-kappa B) is a ubiquitously expressed cellular factor regulated by the cytoplasmic factor inhibitor protein kappa B alpha (I kappa B alpha). Activation of NF-kappa B by cytokines, including tumor necrosis factor-alpha (TNF-alpha), requires the phosphorylation and degradation of I kappa B alpha. An anti-apoptotic role for NF-kappa B has recently been suggested. In the present study, we ascertained whether death-promoting signals and apoptosis mediated by TNF-alpha are suppressed by NF-kappa B in postnatal ventricular myocytes. Stimulation of myocytes with TNF-alpha resulted in a 12.1-fold increase (P < 0.01) in NF-kappa B-dependent gene transcription and DNA binding compared with controls. This was accompanied by a corresponding increase in the NF-kappa B target protein A20 as determined by Western blot analysis. Vital staining revealed that TNF-alpha was not cytotoxic to myocytes and did not provoke apoptosis. Adenovirus-mediated delivery of a nonphosphorylatable form of I kappa B alpha to inactivate NF-kappa B prevented TNF-alpha-stimulated NF-kappa B-dependent gene transcription and nuclear NF-kappa B DNA binding. Importantly, myocytes stimulated with TNF-alpha and defective for NF-kappa B activation resulted in a 2.2-fold increase (P < 0.001) in apoptosis. To our knowledge, the data provide the first indication that a functional NF-kappa B signaling pathway is crucial for suppressing death-promoting signals mediated by TNF-alpha in ventricular myocytes.
Mustapha
S
S
Faculty of Medicine, Department of Physiology, Institute of Cardiovascular Sciences, St. Boniface General Hospital Research Centre, University of Manitoba, Winnipeg, Manitoba, Canada R2H 2A6.
Kirshner
A
A
De Moissac
D
D
Kirshenbaum
L A
LA
D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002452:Cell Count / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D002518:Ceramides / Q000494:pharmacology; D004396:Coloring Agents; D053938:DNA Fragmentation / Q000187:drug effects; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D017930:Genes, Reporter / Q000235:genetics; D006352:Heart Ventricles / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D020672:I-kappa B Proteins; D016297:Mutagenesis, Site-Directed; D009206:Myocardium / Q000166:cytology / Q000378:metabolism*; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000378:metabolism* / Q000494:pharmacology; D011506:Proteins / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D014158:Transcription, Genetic / Q000187:drug effects; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D002518:Ceramides; D004396:Coloring Agents; D004268:DNA-Binding Proteins; D020672:I-kappa B Proteins; D016328:NF-kappa B; C000606206:Nfkbia protein, rat; D011506:Proteins; D014409:Tumor Necrosis Factor-alpha; D000072000:NF-KappaB Inhibitor alpha