The Role of Deoxycytidine Kinase (dCK) in Radiation-Induced Cell Death
The Role of Deoxycytidine Kinase (dCK) in Radiation-Induced Cell Death
复制标题
脱氧胞苷激酶 (dCK) 在辐射诱导的细胞死亡中的作用
DOI：
10.3390/ijms17111939
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发表时间：
2016-11-01
影响因子：
5.6
通讯作者：
Liu, Xiaodong
中科院分区：
文献类型：
--
作者：
Zhong, Rui;Xin, Rui;Liu, Xiaodong
脱氧胞苷激酶 (dCK) 是脱氧核糖核苷回收和许多核苷类似物抗肿瘤活性的关键酶。 dCK 响应电离辐射 (IR) 诱导的 DNA 损伤而被激活，并通过共济失调毛细血管扩张突变 (ATM) 激酶在丝氨酸 74 上磷酸化，以激活细胞周期 G2/M 检查点。然而，dCK 是否在辐射诱导的细胞死亡中发挥作用尚不清楚。在这项研究中，我们通过敲除或表达 dCK 的 WT（野生型）、S74A（废除磷酸化）和 S74E（模拟磷酸化）来对 dCK 表达进行基因修饰。我们发现 dCK 可以减少 IR 诱导的总细胞死亡和细胞凋亡。此外，dCK 会增加 IR 诱导的自噬，而 dCK-S74 是其所必需的。 Western blotting结果显示，IR处理后dCK-WT和dCK-S74E细胞中磷酸化Akt/Akt、磷酸化mTOR/mTOR、磷酸化P70S6K/P70S6K的比值较dCK-S74A细胞显着降低。免疫共沉淀交互实验表明，mTOR 可以与野生型 dCK 相互作用。与对照细胞相比，IR 增加了 dCK 敲低细胞的多倍体性并减少了 G2/M 期停滞。综上所述，磷酸化和活化的 dCK 可以抑制 IR 诱导的细胞死亡，包括细胞凋亡和有丝分裂灾难，并通过 PI3K/Akt/mTOR 途径促进 IR 诱导的自噬。
Deoxycytidine kinase (dCK) is a key enzyme in deoxyribonucleoside salvage and the anti-tumor activity for many nucleoside analogs. dCK is activated in response to ionizing radiation (IR)-induced DNA damage and it is phosphorylated on Serine 74 by the Ataxia-Telangiectasia Mutated (ATM) kinase in order to activate the cell cycle G2/M checkpoint. However, whether dCK plays a role in radiation-induced cell death is less clear. In this study, we genetically modified dCK expression by knocking down or expressing a WT (wild-type), S74A (abrogates phosphorylation) and S74E (mimics phosphorylation) of dCK. We found that dCK could decrease IR-induced total cell death and apoptosis. Moreover, dCK increased IR-induced autophagy and dCK-S74 is required for it. Western blotting showed that the ratio of phospho-Akt/Akt, phospho-mTOR/mTOR, phospho-P70S6K/P70S6K significantly decreased in dCK-WT and dCK-S74E cells than that in dCK-S74A cells following IR treatment. Reciprocal experiment by co-immunoprecipitation showed that mTOR can interact with wild-type dCK. IR increased polyploidy and decreased G2/M arrest in dCK knock-down cells as compared with control cells. Taken together, phosphorylated and activated dCK can inhibit IR-induced cell death including apoptosis and mitotic catastrophe, and promote IR-induced autophagy through PI3K/Akt/mTOR pathway.