TY - JOUR
T1 - Cdt1 Phosphorylation by Cyclin A-dependent Kinases Negatively Regulates Its Function without Affecting Geminin Binding
AU - Sugimoto, Nozomi
AU - Tatsumi, Yasutoshi
AU - Tsurumi, Tatsuya
AU - Matsukage, Akio
AU - Kiyono, Tohru
AU - Nishitani, Hideo
AU - Fujita, Masatoshi
PY - 2004/5/7
Y1 - 2004/5/7
N2 - The current concept regarding cell cycle regulation of DNA replication is that Cdt1, together with origin recognition complex and CDC6 proteins, constitutes the machinery that loads the minichromosome maintenance complex, a candidate replicative helicase, onto chromatin during the G1 phase. The actions of origin recognition complex and CDC6 are suppressed through phosphorylation by cyclin-dependent kinases (Cdks) after S phase to prohibit rereplication. It has been suggested in metazoan cells that the function of Cdt1 is blocked through binding to an inhibitor protein, geminin. However, the functional relationship between the Cdt1-geminin system and Cdks remains to be clarified. In this report, we demonstrate that human Cdt1 is phosphorylated by cyclin A-dependent kinases dependent on its cyclin-binding motif. Cdk phosphorylation resulted in the binding of Cdt1 to the F-box protein Skp2 and subsequent degradation. In contrast, in vitro DNA binding activity of Cdt1 was inhibited by the phosphorylation. However, geminin binding to Cdt1 was not affected by the phosphorylation. Finally we provide evidence that inactivation of Cdk1 results in Cdt1 dephosphorylation and rebinding to chromatin in murine FT210 cells synchronized around the G2/M phase. Taken together, these findings suggest that Cdt1 function is also negatively regulated by the Cdk phosphorylation independent of geminin binding.
AB - The current concept regarding cell cycle regulation of DNA replication is that Cdt1, together with origin recognition complex and CDC6 proteins, constitutes the machinery that loads the minichromosome maintenance complex, a candidate replicative helicase, onto chromatin during the G1 phase. The actions of origin recognition complex and CDC6 are suppressed through phosphorylation by cyclin-dependent kinases (Cdks) after S phase to prohibit rereplication. It has been suggested in metazoan cells that the function of Cdt1 is blocked through binding to an inhibitor protein, geminin. However, the functional relationship between the Cdt1-geminin system and Cdks remains to be clarified. In this report, we demonstrate that human Cdt1 is phosphorylated by cyclin A-dependent kinases dependent on its cyclin-binding motif. Cdk phosphorylation resulted in the binding of Cdt1 to the F-box protein Skp2 and subsequent degradation. In contrast, in vitro DNA binding activity of Cdt1 was inhibited by the phosphorylation. However, geminin binding to Cdt1 was not affected by the phosphorylation. Finally we provide evidence that inactivation of Cdk1 results in Cdt1 dephosphorylation and rebinding to chromatin in murine FT210 cells synchronized around the G2/M phase. Taken together, these findings suggest that Cdt1 function is also negatively regulated by the Cdk phosphorylation independent of geminin binding.
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U2 - 10.1074/jbc.M313175200
DO - 10.1074/jbc.M313175200
M3 - Article
C2 - 14993212
AN - SCOPUS:2442427423
VL - 279
SP - 19691
EP - 19697
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
SN - 0021-9258
IS - 19
ER -