Cyclin-dependent kinases phosphorylate p73 at threonine 86 in a cell cycle-dependent manner and negatively regulate p73.
p73 transcription factors are members of the p53 family and participate in developmental processes and DNA damage response. p73 expression was shown to be regulated during the cell cycle, suggesting that p73 might play a role in cell growth and might be a target for cyclin-dependent kinases. Consistent with this hypothesis, we discovered that p73 interacts physically with various cyclins (A, B, D, and E). Furthermore, cyclin A/CDK1/2, cyclin B/CDK1/2, and cyclin E/CDK2 complexes can phosphorylate multiple p73 isoforms in vitro at threonine 86. A specific antibody directed against phosphorylated Thr86 showed that this site is phosphorylated in vivo and that such phosphorylation is regulated in a cell cycle-dependent manner. Thr86 phosphorylation is induced during S phase and is maximal in the G2/M phase. Accordingly inhibitors of cell growth, such as p16 and serum starvation, reduce Thr86 phosphorylation. Finally, we found that cyclin-dependent kinase (CDK)-dependent Thr86 phosphorylation represses the ability of p73 to induce endogenous p21 expression. Our results demonstrate that p73 proteins are targets of CDK complexes and that phosphorylation on Thr86 by CDKs regulates p73 functions.
Gaiddon
Christian
C
Equipe d'Accecil Signalisations Moléculaires et Neurodégénéréscence, Université Louis Pasteur, Strasbourg 67000, France. gaiddon@neurochem.u-strasbg.fr
Lokshin
Maria
M
Gross
Isabelle
I
Levasseur
Danielle
D
Taya
Yoichi
Y
Loeffler
Jean-Philippe
JP
Prives
Carol
C
D000818:Animals; D001665:Binding Sites; D015153:Blotting, Western; D002453:Cell Cycle; D002460:Cell Line; D002469:Cell Separation; D019925:Cyclin A / Q000378:metabolism; D019926:Cyclin B / Q000378:metabolism; D019927:Cyclin E / Q000378:metabolism; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005434:Flow Cytometry; D016195:G2 Phase; D015971:Gene Expression Regulation, Enzymologic; D017930:Genes, Reporter; D016147:Genes, Tumor Suppressor; D005822:Genetic Vectors; D006801:Humans; D015151:Immunoblotting; D007313:Insecta; D008156:Luciferases / Q000378:metabolism; D008938:Mitosis; D009154:Mutation; D009687:Nuclear Proteins / Q000378:metabolism*; D010766:Phosphorylation; D011233:Precipitin Tests; D011485:Protein Binding; D020033:Protein Isoforms; D017434:Protein Structure, Tertiary; D016196:S Phase; D013912:Threonine / Q000378:metabolism*; D013997:Time Factors; D014158:Transcription, Genetic; D014162:Transfection; D000072160:Tumor Protein p73; D025521:Tumor Suppressor Proteins
D019925:Cyclin A; D019926:Cyclin B; D019927:Cyclin E; D019941:Cyclin-Dependent Kinase Inhibitor p16; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D020033:Protein Isoforms; C000606460:TP73 protein, human; D000072160:Tumor Protein p73; D025521:Tumor Suppressor Proteins; D013912:Threonine; D008156:Luciferases