Centro de Investigación del Cáncer, Universidad de Salamanca/CSIC, 37007 Salamanca, Spain.
J Biol Chem. 2010 Dec 24;285(52):40544-53. doi: 10.1074/jbc.M110.133009. Epub 2010 Oct 18.
The Cdc14 family of serine-threonine phosphatases antagonizes CDK activity by reversing CDK-dependent phosphorylation events. It is well established that the yeast members of this family bring about the M/G1 transition. Budding yeast Cdc14 is essential for CDK inactivation at the end of mitosis and fission yeast Cdc14 homologue Flp1/Clp1 down-regulates Cdc25 to ensure the inactivation of mitotic CDK complexes to trigger cell division. However, the functions of human Cdc14 homologues remain poorly understood. Here we have tested the hypothesis that Cdc14A might regulate Cdc25 mitotic inducers in human cells. We found that increasing levels of Cdc14A delay entry into mitosis by inhibiting Cdk1-cyclin B1 activity. By contrast, lowering the levels of Cdc14A accelerates mitotic entry. Biochemical analyses revealed that Cdc14A acts through key Cdk1-cyclin B1 regulators. We observed that Cdc14A directly bound to and dephosphorylated Cdc25B, inhibiting its catalytic activity. Cdc14A also regulated the activity of Cdc25A at the G2/M transition. Our results indicate that Cdc14A phosphatase prevents premature activation of Cdk1 regulating Cdc25A and Cdc25B at the entry into mitosis.
CDC14 家族的丝氨酸-苏氨酸磷酸酶通过逆转 CDK 依赖性磷酸化事件来拮抗 CDK 活性。已经证实，该家族的酵母成员促使 M/G1 转变。芽殖酵母 CDC14 对于有丝分裂末期 CDK 失活是必需的，裂殖酵母 CDC14 同源物 Flp1/Clp1 下调 Cdc25 以确保有丝分裂 CDK 复合物的失活，从而触发细胞分裂。然而，人类 CDC14 同源物的功能仍知之甚少。在这里，我们检验了这样一个假设，即 Cdc14A 可能调节人类细胞中的 Cdc25 有丝分裂诱导物。我们发现，通过抑制 Cdk1-cyclin B1 的活性，增加 Cdc14A 的水平会延迟有丝分裂的进入。相比之下，降低 Cdc14A 的水平会加速有丝分裂的进入。生化分析表明，Cdc14A 通过关键的 CDK1-cyclin B1 调节剂起作用。我们观察到 Cdc14A 直接与 Cdc25B 结合并使其去磷酸化，抑制其催化活性。Cdc14A 还在 G2/M 转换时调节 Cdc25A 的活性。我们的结果表明，CDC14A 磷酸酶防止 CDK1 的过早激活，从而调节 Cdc25A 和 Cdc25B 在进入有丝分裂时的活性。
