Negative regulation of Wee1 expression and Cdc2 phosphorylation during p53-mediated growth arrest and apoptosis.
The G2 cell cycle checkpoint protects cells from potentially lethal mitotic entry after DNA damage. This checkpoint involves inhibitory phosphorylation of Cdc2 at the tyrosine-15 (Y15) position, mediated in part by the Wee1 protein kinase. Recent evidence suggests that p53 may accelerate mitotic entry after DNA damage and that the override of the G2 checkpoint may play a role in the induction of apoptosis by p53. To determine the biochemical mechanism by which p53 inactivates the G2 checkpoint, the effects of p53 activation on Wee1 expression, Cdc2-Y15 phosphorylation, and cyclin B1-associated Cdc2 kinase activity were examined. Under conditions of either growth arrest or apoptosis, p53 activation resulted in the down-regulation of Wee1 expression and dephosphorylation of Cdc2. A parallel increase in cyclin B1/Cdc2 kinase activity was observed during p53-mediated apoptosis. Negative regulation of the Wee1 expression and Cdc2 phosphorylation by p53 was also evident in thymus tissue from p53+/+ mice but not from p53-/- mice. Inactivation of the G2 checkpoint may contribute to the tumor suppressor activity of p53.
Department of Surgery, The Vanderbilt Cancer Center, Nashville Veterans Affairs Medical Center, Tennessee 37232, USA.
S D
SD
Leach
C D
CD
Scatena
C J
CJ
Keefer
H A
HA
Goodman
S Y
SY
Song
L
L
Yang
J A
JA
Pietenpol
D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000502:physiology*; D015153:Blotting, Western; D016203:CDC2 Protein Kinase / Q000378:metabolism*; D018797:Cell Cycle Proteins; D002455:Cell Division / Q000502:physiology; D019926:Cyclin B / Q000378:metabolism; D056744:Cyclin B1; D015536:Down-Regulation; D004622:Embryo, Mammalian; D004789:Enzyme Activation; D005347:Fibroblasts / Q000166:cytology; D016195:G2 Phase / Q000502:physiology; D016399:Lymphoma, T-Cell / Q000378:metabolism; D051379:Mice; D015739:Nocodazole / Q000494:pharmacology; D009687:Nuclear Proteins; D010766:Phosphorylation; D011487:Protein Conformation; D011505:Protein-Tyrosine Kinases / Q000096:biosynthesis*; D051381:Rats; D014170:Transformation, Genetic; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000502:physiology*
D000970:Antineoplastic Agents; C534700:Ccnb1 protein, mouse; C534701:Ccnb1 protein, rat; D018797:Cell Cycle Proteins; D019926:Cyclin B; D056744:Cyclin B1; D009687:Nuclear Proteins; D016159:Tumor Suppressor Protein p53; D011505:Protein-Tyrosine Kinases; C499348:Wee1 protein, mouse; D016203:CDC2 Protein Kinase; D015739:Nocodazole