DNA-dependent protein kinase acts upstream of p53 in response to DNA damage.
The tumour suppressor p53 becomes activated as a transcription factor in response to DNA damage, but the mechanism for this activation is unclear. A good candidate for an upstream activator of p53 is the DNA-dependent protein kinase (DNA-PK) that depends on the presence of DNA breaks for its activity. Here we investigate the link between DNA damage and the activation of DNA-PK and of p53. To determine whether DNA-PK is an upstream mediator of the p53 DNA-damage response, we analysed a severe combined-immunodeficiency (SCID) mouse cell line, SCGR11, and the human glioma cell line M059J . Both cell lines lack any detectable DNA-PK activity. We find that p53 is incapable of binding to DNA in the absence of DNA-PK, that DNA-PK is necessary but not sufficient for activation of p53 sequence-specific DNA binding, and that this activation occurs in response to DNA damage. Our results establish DNA-PK as a link between DNA damage and p53 activation, and reveal the existence of a mammalian DNA-damage-response pathway.
Department of Microbiology and Infectious Diseases, University of Calgary, Alberta, Canada.
R A
RA
Woo
K G
KG
McLure
S P
SP
Lees-Miller
D E
DE
Rancourt
P W
PW
Lee
D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000096:biosynthesis / Q000235:genetics; D004247:DNA / Q000378:metabolism; D004249:DNA Damage; D051747:DNA-Activated Protein Kinase; D004268:DNA-Binding Proteins; D004789:Enzyme Activation; D004791:Enzyme Inhibitors; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D016513:Mice, SCID; D008969:Molecular Sequence Data; D009687:Nuclear Proteins; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014162:Transfection; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*
C493956:CDKN1A protein, human; C493957:Cdkn1a protein, mouse; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D009687:Nuclear Proteins; D016159:Tumor Suppressor Protein p53; D004247:DNA; D051747:DNA-Activated Protein Kinase; C497263:PRKDC protein, human; D017346:Protein Serine-Threonine Kinases