STAT-1 interacts with p53 to enhance DNA damage-induced apoptosis.
The STAT-1 transcription factor has been implicated as a tumor suppressor by virtue of its ability to inhibit cell growth and promoting apoptosis. However, the mechanisms by which STAT-1 mediates these effects remain unclear. Using human and mouse STAT-1-deficient cells, we show here that STAT-1 is required for optimal DNA damage-induced apoptosis. The basal level of the p53 inhibitor Mdm2 is increased in STAT-1(-/-) cells, suggesting that STAT-1 is a negative regulator of Mdm2 expression. Correspondingly, both basal p53 levels, and those induced by DNA damage were lower in STAT-1(-/-) cells. In agreement with this lower p53 response to DNA damage in cells lacking STAT-1, the induction of p53 responsive genes, such as Bax, Noxa, and Fas, was reduced in STAT-1-deficient cells. Conversely, STAT-1 overexpression enhances transcription of these genes, an effect that is abolished if the p53 response element in their promoters is mutated. Moreover, STAT-1 interacts directly with p53, an association, which is enhanced following DNA damage. Therefore, in addition to negatively regulating Mdm2, STAT-1 also acts as a coactivator for p53. Hence STAT-1 is another member of a growing family of protein partners able to modulate the p53-activated apoptotic pathway.
Townsend
Paul A
PA
Medical Molecular Biology Unit, Institute of Child Health, University College London, 30 Guilford Street, London WC1N 1EH, United Kingdom.
Scarabelli
Tiziano M
TM
Davidson
Sean M
SM
Knight
Richard A
RA
Latchman
David S
DS
Stephanou
Anastasis
A
D000818:Animals; D017209:Apoptosis; D001665:Binding Sites; D015153:Blotting, Western; D019941:Cyclin-Dependent Kinase Inhibitor p16; D004249:DNA Damage; D004268:DNA-Binding Proteins / Q000378:metabolism*; D017930:Genes, Reporter; D005982:Glutathione Transferase / Q000378:metabolism; D006801:Humans; D007371:Interferon-gamma / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D018613:Microscopy, Confocal; D009154:Mutation; D009687:Nuclear Proteins; D010766:Phosphorylation; D011233:Precipitin Tests; D011401:Promoter Regions, Genetic; D017434:Protein Structure, Tertiary; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051736:Proto-Oncogene Proteins c-mdm2; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050794:STAT1 Transcription Factor; D013997:Time Factors; D015534:Trans-Activators / Q000378:metabolism*; D014158:Transcription, Genetic; D014162:Transfection; D025803:Tumor Suppressor Protein p14ARF / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*
C417743:Cdkn2a protein, mouse; D019941:Cyclin-Dependent Kinase Inhibitor p16; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D011993:Recombinant Fusion Proteins; D050794:STAT1 Transcription Factor; C494079:STAT1 protein, human; C494080:Stat1 protein, mouse; D015534:Trans-Activators; D025803:Tumor Suppressor Protein p14ARF; D016159:Tumor Suppressor Protein p53; D007371:Interferon-gamma; C497206:MDM2 protein, human; C497207:Mdm2 protein, mouse; D051736:Proto-Oncogene Proteins c-mdm2; D005982:Glutathione Transferase