title: Reciprocal inhibition of p53 and nuclear factor-kappaB transcriptional activities determines cell survival or death in neurons.
abstract: The tumor suppressor and transcription factor p53 is a key modulator of cellular stress responses, and activation of p53 precedes apoptosis in many cell types. Controversial reports exist on the role of the transcription factor nuclear factor-kappaB (NF-kappaB) in p53-mediated apoptosis, depending on the cell type and experimental conditions. Therefore, we sought to elucidate the role of NF-kappaB in p53-mediated neuron death. In cultured neurons DNA damaging compounds induced activation of p53, whereas NF-kappaB activity declined significantly. The p53 inhibitor pifithrin-alpha (PFT) preserved NF-kappaB activity and protected neurons against apoptosis. Immunoprecipitation experiments revealed enhanced p53 binding to the transcriptional cofactor p300 after induction of DNA damage, whereas binding of p300 to NF-kappaB was reduced. In contrast, PFT blocked the interaction of p53 with the cofactor, whereas NF-kappaB binding to p300 was enhanced. Most interestingly, similar results were observed after oxygen glucose deprivation in cultured neurons and in ischemic brain tissue. Ischemia-induced repression of NF-kappaB activity was prevented and brain damage was reduced by the p53 inhibitor PFT in a dose-dependent manner. It is concluded that a balanced competitive interaction of p53 and NF-kappaB with the transcriptional cofactor p300 exists in neurons. Exposure of neurons to lethal stress activates p53 and disrupts NF-kappaB binding to p300, thereby blocking NF-kappaB-mediated survival signaling. Inhibitors of p53 provide pronounced neuroprotective effects because they block p53-mediated induction of cell death and concomitantly enhance NF-kappaB-induced survival signaling.
mesh_terms: D000123:Acetyltransferases / Q000378:metabolism; D000818:Animals; D052160:Benzothiazoles; D002545:Brain Ischemia / Q000188:drug therapy / Q000503:physiopathology; D018797:Cell Cycle Proteins / Q000378:metabolism; D016923:Cell Death / Q000235:genetics / Q000502:physiology; D015687:Cell Hypoxia / Q000502:physiology; D002470:Cell Survival / Q000235:genetics / Q000502:physiology; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D005260:Female; D017930:Genes, Reporter; D005947:Glucose / Q000378:metabolism; D051548:Histone Acetyltransferases; D006710:Homocysteine / Q000633:toxicity; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D016328:NF-kappa B / Q000235:genetics* / Q000378:metabolism; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D018696:Neuroprotective Agents / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D017208:Rats, Wistar; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013312:Stress, Physiological / Q000378:metabolism; D013844:Thiazoles / Q000494:pharmacology; D014050:Toluene / Q000031:analogs & derivatives* / Q000494:pharmacology; D014157:Transcription Factors; D014158:Transcription, Genetic / Q000502:physiology*; D016159:Tumor Suppressor Protein p53 / Q000037:antagonists & inhibitors / Q000235:genetics*; D050880:p300-CBP Transcription Factors; D000099224:p300-CBP-Associated Factor
chemical_list: D000123:Acetyltransferases; D052160:Benzothiazoles; D018797:Cell Cycle Proteins; D005947:Glucose; D051548:Histone Acetyltransferases; D006710:Homocysteine; D016328:NF-kappa B; D018696:Neuroprotective Agents; D013844:Thiazoles; D014050:Toluene; D014157:Transcription Factors; D016159:Tumor Suppressor Protein p53; D050880:p300-CBP Transcription Factors; D000099224:p300-CBP-Associated Factor; C121565:pifithrin