TY - JOUR
T1 - Functional activation of p53 via phosphorylation following DNA damage by UV but not γ radiation
AU - Kapoor, Mini
AU - Lozano, Guillermina
PY - 1998/3/17
Y1 - 1998/3/17
N2 - The tumor suppressor p53 is a nuclear phosphoprotein in which DNA- binding activity is increased on exposure to DNA-damaging agents such as UV or γ radiation by unknown mechanisms. Because phosphorylation of p53 at the casein kinase (CK) II site activates p53 for DNA-binding function in vitro, we sought to determine the in vivo relevance of phosphorylation at this site after UV and γ radiation. A polyclonal antibody was generated that binds to bacterially expressed p53 only when phosphorylated in vitro by CK II. Using this antibody, we showed that p53 is phosphorylated at the CK II site upon UV treatment of early passage rat embryo fibroblasts and RKO cells. In addition, DNA-binding assays indicated that phosphorylated p53 bound to a p53- responsive element, suggesting functional activation. However, γ radiation, which also stabilizes p53, did not result in phosphorylation at the CK II site. These results indicate that phosphorylation at the CK II site is one of the post-translational mechanisms through which p53 is activated in response to UV radiation and that different mechanisms activate p53 after DNA damage by γ radiation.
AB - The tumor suppressor p53 is a nuclear phosphoprotein in which DNA- binding activity is increased on exposure to DNA-damaging agents such as UV or γ radiation by unknown mechanisms. Because phosphorylation of p53 at the casein kinase (CK) II site activates p53 for DNA-binding function in vitro, we sought to determine the in vivo relevance of phosphorylation at this site after UV and γ radiation. A polyclonal antibody was generated that binds to bacterially expressed p53 only when phosphorylated in vitro by CK II. Using this antibody, we showed that p53 is phosphorylated at the CK II site upon UV treatment of early passage rat embryo fibroblasts and RKO cells. In addition, DNA-binding assays indicated that phosphorylated p53 bound to a p53- responsive element, suggesting functional activation. However, γ radiation, which also stabilizes p53, did not result in phosphorylation at the CK II site. These results indicate that phosphorylation at the CK II site is one of the post-translational mechanisms through which p53 is activated in response to UV radiation and that different mechanisms activate p53 after DNA damage by γ radiation.
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U2 - 10.1073/pnas.95.6.2834
DO - 10.1073/pnas.95.6.2834
M3 - Article
C2 - 9501176
AN - SCOPUS:0032539816
SN - 0027-8424
VL - 95
SP - 2834
EP - 2837
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 6
ER -