Akt/protein kinase B-dependent phosphorylation and inactivation of WEE1Hu promote cell cycle progression at G2/M transition
Akt/protein kinase B-dependent phosphorylation and inactivation of WEE1Hu promote cell cycle progression at G2/M transition
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DOI：
10.1128/mcb.25.13.5725-5737.2005
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发表时间：
2005-07-01
影响因子：
5.3
通讯作者：
Tsuruo, T
中科院分区：
文献类型：
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作者：
Katayama, K;Fujita, N;Tsuruo, T
已知丝氨酸/苏氨酸激酶Akt通过激活细胞周期蛋白/Cdk激酶以及使Cdk抑制剂失活来调控G₁期细胞周期，从而促进细胞生长。然而，Akt如何调控G₂/M期仍不清楚。在此，我们表明Akt可抵消WEE1Hu的功能。化疗药物或磷脂酰肌醇 - 3 - 羟基激酶抑制剂LY294002使Akt失活，会诱导G₂/M期阻滞以及Cdc2的抑制性磷酸化。由于wee1hu基因沉默可完全抑制Cdc2磷酸化的增加，所以WEE1Hu与Akt失活诱导的G₂/M期阻滞有关。进一步分析显示，在S期到G₂期，Akt直接与WEE1Hu结合并使其磷酸化。丝氨酸 - 642被确定为一个依赖Akt的磷酸化位点。WEE1Hu激酶活性不受丝氨酸 - 642磷酸化的影响。我们发现丝氨酸 - 642磷酸化促进了WEE1Hu的细胞质定位。核质转位是由依赖磷酸化的WEE1Hu与14 - 3 - 3θ结合介导的，而不是与14 - 3 - 3β或 - σ结合。这些结果表明，Akt通过诱导依赖磷酸化的14 - 3 - 3θ结合以及WEE1Hu的细胞质定位来促进G₂/M期细胞周期进程。
The serine/threonine kinase Akt is known to promote cell growth by regulating the cell cycle in G(1) phase through activation of cyclin/Cdk kinases and inactivation of Cdk inhibitors. However, how the G(2)/M phase is regulated by Akt remains unclear. Here, we show that Akt counteracts the function of WEE1Hu. Inactivation of Akt by chemotherapeutic drugs or the phosphatidylinositide-3-OH kinase inhibitor LY294002 induced G(2)/M arrest together with the inhibitory phosphorylation of Cdc2. Because the increased Cdc2 phosphorylation was completely suppressed by wee1hu gene silencing, WEE1Hu was associated with G(2)/M arrest induced by Akt inactivation. Further analyses revealed that Akt directly bound to and phosphorylated WEE1Hu during the S to G(2) phase. Serine-642 was identified as an Akt-dependent phosphorylation site. WEE1Hu kinase activity was not affected by serine-642 phosphorylation. We revealed that serine-642 phosphorylation promoted cytoplasmic localization of WEE1Hu. The nuclear-to-cytoplasmic translocation was mediated by phosphorylation-dependent WEE1Hu binding to 14-3-3 theta but not 14-3-3 beta or -sigma. These results indicate that Akt promotes G(2)/M cell cycle progression by inducing phosphorylation-dependent 14-3-3 theta binding and cytoplasmic localization of WEE1Hu.