Polo-like kinase 1 phosphorylates cyclin B1 and targets it to the nucleus during prophase
Polo-like kinase 1 phosphorylates cyclin B1 and targets it to the nucleus during prophase
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DOI：
10.1038/35065617
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发表时间：
2001-03-08
期刊：
影响因子：
64.8
通讯作者：
Nishida, E
中科院分区：
文献类型：
--
作者：
Toyoshima-Morimoto, F;Taniguchi, E;Nishida, E
在脊椎动物细胞中，Cdc 2-细胞周期蛋白B1（MPF 1 -3）在前期（4-6）的核进入被认为是M期事件的诱导和协调所必需的（7-12）。细胞周期蛋白B1的磷酸化是其核转位的核心（8，13，14），但负责的激酶仍然未知。在这里，我们已经从非洲爪蟾M期提取物中纯化了一种蛋白激酶，该蛋白激酶磷酸化细胞周期蛋白B1的核输出信号序列（10，13，15）中间的关键丝氨酸残基（S147）。我们已经将这种激酶鉴定为Plx 1（参考文献16），它是Polo样激酶（Plk）-1（参考文献17、18）的爪蟾同源物。在HeLa细胞的细胞周期进程中，内源性Plk 1对S147和/或S133的激酶活性的变化与细胞提取物中的激酶活性相关。抗Plk 1抗体消除M期提取物对S147和/或S133的激酶活性。抗磷酸化S147抗体仅在G2/M期与细胞周期蛋白B1特异性反应。突变的细胞周期蛋白B1中，S133和S147被丙氨酸取代仍然在细胞质中，而野生型细胞周期蛋白B1积累在细胞核中的前期。组成型活性Plk 1的共表达刺激细胞周期蛋白B1的核进入。我们的研究结果表明，Plk 1可能参与在前期MPF的核靶向。
In vertebrate cells, the nuclear entry of Cdc2-cyclin B1 (MPF1-3) during prophase(4-6) is thought to be essential for the induction and coordination of M-phase events(7-12). Phosphorylation of cyclin B1 is central to its nuclear translocation(8,13,14), but the kinases that are responsible remain unknown. Here we have purified a protein kinase from Xenopus M-phase extracts that phosphorylates a crucial serine residue (S147) in the middle of the nuclear export signal sequence(10,13,15) of cyclin B1. We have identified this kinase as Plx1 (ref. 16), a Xenopus homologue of Polo-like kinase (Plk)-1 (refs 17, 18). During cell-cycle progression in HeLa cells, a change in the kinase activity of endogenous Plk1 toward S147 and/or S133 correlates with a kinase activity in the cell extracts. An anti-Plk1 antibody depletes the M-phase extracts of the kinase activity toward S147 and/or S133. An anti-phospho-S147 antibody reacts specifically with cyclin B1 only during G2/M phase. A mutant cyclin B1 in which S133 and S147 are replaced by alanines remains in the cytoplasm, whereas wild-type cyclin B1 accumulates in the nucleus during prophase. Co-expression of constitutively active Plk1 stimulates nuclear entry of cyclin B1. Our results indicate that Plk1 may be involved in targeting MPF to the nucleus during prophase.