Control of the G2/M checkpoints after exposure to low doses of ionising radiation: Implications for hyper-radiosensitivity
Control of the G2/M checkpoints after exposure to low doses of ionising radiation: Implications for hyper-radiosensitivity
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DOI：
10.1016/j.dnarep.2009.10.006
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发表时间：
2010-01-02
期刊：
影响因子：
3.8
通讯作者：
Favaudon, Vincent
中科院分区：
文献类型：
--
作者：
Fernet, Marie;Megnin-Chanet, Frederique;Favaudon, Vincent
两个分子上不同的G2/M细胞周期的逮捕后，暴露于电离辐射（IR）取决于细胞周期室中的细胞被照射诱导。本研究的目的是确定是否有阈值剂量的激活，并调查的分子途径和可能的联系之间的G2到M过渡和超辐射敏感性（HRS）。对两种G2不同步或富集的人胶质母细胞瘤细胞系（T98 G-HRS（+）和U373-HRS（-））进行辐照，并使用流式细胞术和BrdU或组蛋白H3磷酸化分析评估细胞周期进展，并使用克隆形成试验测量辐射存活率。使用化学抑制剂研究了ATM，Wee 1和PARP的参与。我们发现，无论是在G1期或S期的细胞周期照射后，以剂量依赖的方式在G2短暂积累暴露于低至0.2戈伊的剂量。只有Wee 1抑制减少这种G2积累。在G2中辐照后发现G2到M转变的阻断，但仅在阈值剂量以上发生，这是细胞系依赖性的，并且在暴露于0.5戈伊以上的剂量后需要ATM活性。未能激活这个早期G2/M检查点与低剂量放射增敏相关。这些结果提供的证据表明，暴露于低剂量的IR后，两个不同的G2/M检查点被激活，每个以剂量依赖性的方式，具有不同的阈值剂量和涉及不同的损伤信号通路，并确认早期G2/M检查点和超辐射敏感性之间的联系。(C)2009爱思唯尔有限公司版权所有。
Two molecularly distinct G2/M cell cycle arrests are induced after exposure to ionising radiation (IR) depending on the cell cycle compartment in which the cells are irradiated. The aims of this study were to determine whether there are threshold doses for their activation and investigate the molecular pathways and possible links between the G2 to M transition and hyper-radiosensitivity (HRS). Two human glioblastoma cell lines (T98G-HRS(+) and U373-HRS(-)) unsynchronized or enriched in G2 were irradiated and flow cytometry with BrdU or histone H3 phosphorylation analysis used to assess cell cycle progression and a clonogenic assay to measure radiation survival. The involvement of ATM, Wee1 and PARP was studied using chemical inhibitors. We found that cells irradiated in either the G1 or S phase of the cell cycle transiently accumulate in G2 in a dose-dependent manner after exposure to doses as low as 0.2 Gy. Only Wee1 inhibition reduced this G2 accumulation. A block of the G2 to M transition was found after irradiation in G2 but occurs only above a threshold dose, which is cell line dependent, and requires ATM activity after exposure to doses above 0.5 Gy. A failure to activate this early G2/M checkpoint correlates with low dose radiosensitization. These results provide evidence that after exposure to low doses of IR two distinct G2/M checkpoints are activated, each in a dose-dependent manner, with distinct threshold doses and involving different damage signalling pathways and confirm links between the early G2/M checkpoint and hyper-radiosensitivity. (C) 2009 Elsevier B.V. All rights reserved.