Role of inhibitory CDC2 phosphorylation in radiation-induced G2 arrest in human cells.
Role of inhibitory CDC2 phosphorylation in radiation-induced G2 arrest in human cells.
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DOI：
10.1083/jcb.134.4.963
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发表时间：
1996-08
期刊：
影响因子：
--
通讯作者：
Morgan DO
中科院分区：
文献类型：
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作者：
Jin P;Gu Y;Morgan DO
有丝分裂促进激酶 CDC2-cyclin B 的活性通常在 S 期和 G2 期通过 Thr14 和 Tyr15 的抑制性磷酸化而受到抑制。这项工作探讨了这些磷酸化可能导致 DNA 损伤后人类细胞中发生的 G2 停滞。建立的 HeLa 细胞系中，CDC2AF（一种 Thr14 和 Tyr15 不能磷酸化的突变体）由四环素抑制型启动子表达。 CDC2AF的表达不会在用DNA合成抑制剂抑制在S期开始时的细胞中诱导有丝分裂事件，但会在进展到S期和G2的细胞中诱导低水平的过早染色质浓缩。 CDC2AF 的表达大大减少了细胞在 S 期接受 X 射线照射时导致的 G2 延迟。然而，仍然观察到显着的 G2 延迟，并伴有高 CDC2 相关激酶活性。野生型CDC2或相关激酶CDK2AF的表达对辐射引起的延迟没有影响。因此，CDC2 的抑制性磷酸化以及其他未定义的机制会延迟 DNA 损伤后的有丝分裂。
The activity of the mitosis-promoting kinase CDC2-cyclin B is normally suppressed in S phase and G2 by inhibitory phosphorylation at Thr14 and Tyr15. This work explores the possibility that these phosphorylations are responsible for the G2 arrest that occurs in human cells after DNA damage. HeLa cell lines were established in which CDC2AF, a mutant that cannot be phosphorylated at Thr14 and Tyr15, was expressed from a tetracycline-repressible promoter. Expression of CDC2AF did not induce mitotic events in cells arrested at the beginning of S phase with DNA synthesis inhibitors, but induced low levels of premature chromatin condensation in cells progressing through S phase and G2. Expression of CDC2AF greatly reduced the G2 delay that resulted when cells were X- irradiated in S phase. However, a significant G2 delay was still observed and was accompanied by high CDC2-associated kinase activity. Expression of wild-type CDC2, or the related kinase CDK2AF, had no effect on the radiation-induced delay. Thus, inhibitory phosphorylation of CDC2, as well as additional undefined mechanisms, delay mitosis after DNA damage.