Ethanol metabolism activates cell cycle checkpoint kinase, Chk2.
Ethanol metabolism activates cell cycle checkpoint kinase, Chk2.
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乙醇代谢激活细胞周期检查点激酶 Chk2。
DOI：
10.1016/j.alcohol.2011.07.005
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发表时间：
2011
期刊：
影响因子：
--
通讯作者：
Nuss,RobertF
中科院分区：
文献类型：
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作者：
Clemens,DahnL;Schneider,KatrinaJMahan;Nuss,RobertF
慢性乙醇滥用导致肝细胞损伤并损害肝细胞复制。我们以前已经表明，乙醇代谢导致细胞周期停滞在G2/M转换，这是部分介导的抑制磷酸化的细胞周期蛋白依赖性激酶，Cdc 2。为了进一步阐明乙醇代谢介导G2/M期阻滞的机制，我们研究了Cdc 2活性上游调节因子的参与。Cdc 2由磷酸酶Cdc 25 C激活。Cdc 25 C的活性反过来可以由检查点激酶Chk 2调节，Chk 2由激酶共济失调毛细血管扩张突变（ATM）调节。为了研究Cdc 2活性的调节剂的参与，在存在或不存在25 mM乙醇的情况下培养VA-13细胞，所述VA-13细胞是经修饰以有效表达醇脱氢酶的Hep G2细胞。进行免疫印迹以确定乙醇代谢对Cdc 25 C、Chk 2和ATM活化的影响。乙醇代谢增加了ATM和Chk 2的活性形式，以及Cdc 25 C的磷酸化形式。此外，ATM的抑制导致大约50%的细胞从G2/M细胞周期停滞中被拯救出来，并改善了Cdc 2的抑制性磷酸化。我们的研究结果表明，乙醇代谢激活ATM。ATM可以激活检查点激酶Chk 2，导致Cdc 25 C的磷酸化，并最终导致非活性Cdc 2的积累。这可能部分解释了乙醇代谢介导的肝细胞复制障碍，这可能在酒精性肝损伤的发生和发展中起重要作用。
Chronic ethanol abuse results in hepatocyte injury and impairs hepatocyte replication. We have previously shown that ethanol metabolism results in cell cycle arrest at the G2/M transition, which is partially mediated by inhibitory phosphorylation of the cyclin-dependent kinase, Cdc2. To further delineate the mechanisms by which ethanol metabolism mediates this G2/M arrest, we investigated the involvement of upstream regulators of Cdc2 activity. Cdc2 is activated by the phosphatase Cdc25C. The activity of Cdc25C can, in turn, be regulated by the checkpoint kinase, Chk2, which is regulated by the kinase ataxia telangiectasia mutated (ATM). To investigate the involvement of the regulators of Cdc2 activity, VA-13 cells, which are Hep G2 cells modified to efficiently express alcohol dehydrogenase, were cultured in the presence or absence of 25 mM ethanol. Immunoblots were performed to determine the effects of ethanol metabolism on the activation of Cdc25C, Chk2, and ATM. Ethanol metabolism increased the active forms of ATM and Chk2, as well as the phosphorylated form of Cdc25C. Additionally, inhibition of ATM resulted in approximately 50% of the cells being rescued from the G2/M cell cycle arrest and ameliorated the inhibitory phosphorylation of Cdc2. Our findings demonstrated that ethanol metabolism activates ATM. ATM can activate the checkpoint kinase Chk2, resulting in phosphorylation of Cdc25C and ultimately in the accumulation of inactive Cdc2. This may, in part, explain the ethanol metabolism–mediated impairment in hepatocyte replication, which may be important in the initiation and progression of alcoholic liver injury.