H2AX Is Required for Cell Cycle Arrest via the p53/p21 Pathway
H2AX Is Required for Cell Cycle Arrest via the p53/p21 Pathway
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DOI：
10.1128/mcb.01830-08
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发表时间：
2009-05-15
影响因子：
5.3
通讯作者：
Beard, Peter
中科院分区：
文献类型：
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作者：
Fragkos, Michalis;Jurvansuu, Jaana;Beard, Peter
H2 AX的磷酸化（gamma H2 AX）是由复制停滞诱导的DNA损伤的早期迹象。然而，H2 AX在这种类型的DNA损伤修复中的作用仍不清楚。在这项研究中，我们使用灭活的腺相关病毒（AAV）诱导停滞的复制叉信号，并研究γ H2 AX的功能。对AAV的细胞应答提供了研究γ H2 AX功能的独特模型，因为感染引起泛核H2 AX磷酸化而没有对宿主基因组造成任何损伤的迹象。我们发现，泛核γ-H2 AX的形成是ATR过度活化和扩散的结果，但不依赖于ATM。用RNA干扰抑制H2 AX或使用H2 AX缺陷细胞表明，γ H2 AX与停滞复制诱导的DNA修复灶的形成和维持有关。然而，在没有H2 AX的情况下，含有AAV的细胞显示p21的蛋白体依赖性降解，随后是半胱天冬酶依赖性有丝分裂灾难。相比之下，H2 AX-熟练的细胞以及H2 AX-互补的H2 AX（-/-）细胞通过增加p21水平和阻止细胞周期来反应。这些结果确立了H2 AX在p53/p21通路中的新作用，并表明H2 AX是复制停滞后p21诱导的细胞周期停滞所必需的。
Phosphorylation of H2AX (gamma H2AX) is an early sign of DNA damage induced by replication stalling. However, the role of H2AX in the repair of this type of DNA damage is still unclear. In this study, we used an inactivated adeno-associated virus (AAV) to induce a stalled replication fork signal and investigate the function of gamma H2AX. The cellular response to AAV provides a unique model to study gamma H2AX function, because the infection causes pannuclear H2AX phosphorylation without any signs of damage to the host genome. We found that pannuclear gamma H2AX formation is a result of ATR overactivation and diffusion but is independent of ATM. The inhibition of H2AX with RNA interference or the use of H2AX-deficient cells showed that gamma H2AX is dispensable for the formation and maintenance of DNA repair foci induced by stalled replication. However, in the absence of H2AX, the AAV-containing cells showed proteosome-dependent degradation of p21, followed by caspase-dependent mitotic catastrophe. In contrast, H2AX-proficient cells as well as H2AX-complemented H2AX(-/-) cells reacted by increasing p21 levels and arresting the cell cycle. The results establish a new role for H2AX in the p53/p21 pathway and indicate that H2AX is required for p21-induced cell cycle arrest after replication stalling.