TTK/Mps1 controls nuclear targeting of c-Abl by 14-3-3-coupled phosphorylation in response to oxidative stress
TTK/Mps1 controls nuclear targeting of c-Abl by 14-3-3-coupled phosphorylation in response to oxidative stress
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DOI：
10.1038/onc.2008.334
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发表时间：
2008-12-01
期刊：
影响因子：
8
通讯作者：
Yoshida, K.
中科院分区：
文献类型：
--
作者：
Nihira, K.;Taira, N.;Yoshida, K.
暴露于遗传毒性应激后，c-Abl酪氨酸激酶从细胞质14-3-3蛋白释放，然后靶向细胞核。c-Abl中Thr 735的磷酸化对于与14-3-3的结合至关重要;然而，负责这种磷酸化的激酶是未知的。在这里，我们确定CLK 1，CLK 4，MST 1，MST 2和TTK（也称为Mps 1）作为新的Thr 735激酶在体外表达克隆策略，使用磷酸化。c抗体。我们还表明，这些激酶的异位表达是能够在细胞中的Thr 735磷酸化。重要的是，在暴露于氧化应激时，Thr 735的磷酸化被瞬时上调，并且这种磷酸化的状态在针对CLK 1、CLK 4、MST 1或MST 2沉默的细胞中保持不变。相比之下，TTK的敲低减弱了Thr 735的磷酸化，表明TTK是磷酸化Thr 735的生理激酶。与这些结果一致，我们表明，在沉默TTK的细胞中，c-Abl即使在无应激条件下也在细胞核中积累，并且在氧化应激后没有进一步靶向细胞核。此外，通过敲低TTK使c-Abl的核截留增强氧化应激诱导的细胞凋亡。这些发现提供了TTK在Thr 735磷酸化c-Abl的证据，并且这种磷酸化对c-Abl的细胞质螯合是重要的。
Upon exposure to genotoxic stress, the c-Abl tyrosine kinase is released from cytoplasmic 14-3-3 proteins and then is targeted to the nucleus. Phosphorylation of Thr735 in c-Abl is critical for binding to 14-3-3; however, kinases responsible for this phosphorylation are unknown. Here, we identify CLK1, CLK4, MST1, MST2 and TTK (also known as Mps1) as novel Thr735 kinases in vitro by expression cloning strategy using phosphospeci. c antibody. We also demonstrate that ectopic expression of these kinases is capable for phosphorylation of Thr735 in cells. Importantly, upon exposure to oxidative stress, phosphorylation of Thr735 is transiently upregulated, and the status of this phosphorylation remains unchanged in cells silenced for CLK1, CLK4, MST1 or MST2. By contrast, knockdown of TTK attenuates phosphorylation of Thr735, suggesting that TTK is a physiological kinase that phosphorylates Thr735. In concert with these results, we show that, in cells silenced for TTK, c-Abl is accumulated in the nucleus even in unstressed condition and no further targeting into the nucleus occurs after oxidative stress. Moreover, nuclear entrapment of c-Abl by knocking down TTK enhances oxidative stress-induced apoptosis. These findings provide evidence that TTK phosphorylates c-Abl at Thr735 and that this phosphorylation is of importance to the cytoplasmic sequestration of c-Abl.