title: Activation of p73 and induction of Noxa by DNA damage requires NF-kappa B.
abstract: Although the transcription factor NF-kappaB is most clearly linked to the inhibition of extrinsic apoptotic signals such as TNFalpha by upregulating known anti-apoptotic genes, NF-kappaB has also been proposed to be required for p53-induced apoptosis in transformed cells. However, the involvement of NF-kappaB in this process is poorly understood. Here we investigate this mechanism and show that in transformed MEFs lacking NF-kappaB (p65-null cells) genotoxin-induced cytochrome c release is compromised. To further address how NF-kappaB contributes to apoptosis, gene profiling by microarray analysis of MEFs was performed, revealing that NF-kappaB is required for expression of Noxa, a pro-apoptotic BH3-only protein that is induced by genotoxins and that triggers cytochrome c release. Moreover, we find that in the absence of NF-kappaB, genotoxin treatment cannot induce Noxa mRNA expression. Noxa expression had been shown to be regulated directly by genes of the p53 family, like p73 and p63, following genotoxin treatment. Here we show that p73 is activated after genotoxin treatment only in the presence of NF-kappaB and that p73 induces Noxa gene expression through the p53 element in the promoter. Together our data provides an explanation for how loss of NF-kappaB abrogates genotoxin-induced apoptosis.
authors.affiliation: Apoptosis Section, NCI-Frederick, Frederick, MD 21702, USA. agmartin@inbiomed.org
authors.forename: Angel G
authors.initials: AG
authors.lastname: Martin
authors.forename: Jason
authors.initials: J
authors.lastname: Trama
authors.forename: Diane
authors.initials: D
authors.lastname: Crighton
authors.forename: Kevin M
authors.initials: KM
authors.lastname: Ryan
authors.forename: Howard O
authors.initials: HO
authors.lastname: Fearnhead
mesh_terms: D000818:Animals; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology; D017209:Apoptosis; D002460:Cell Line; D045304:Cytochromes c / Q000378:metabolism; D004249:DNA Damage; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005047:Etoposide / Q000494:pharmacology; D020869:Gene Expression Profiling; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D006801:Humans; D053858:Metabolic Networks and Pathways / Q000187:drug effects; D051379:Mice; D009687:Nuclear Proteins / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis* / Q000235:genetics; D051996:Transcription Factor RelA / Q000502:physiology*; D015533:Transcriptional Activation; D000072160:Tumor Protein p73; D025521:Tumor Suppressor Proteins / Q000378:metabolism*
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; C408009:Pmaip1 protein, mouse; D019253:Proto-Oncogene Proteins c-bcl-2; C498144:Rela protein, mouse; C000606460:TP73 protein, human; D051996:Transcription Factor RelA; C000606368:Trp73 protein, mouse; D000072160:Tumor Protein p73; D025521:Tumor Suppressor Proteins; D005047:Etoposide; D045304:Cytochromes c