Nuclear Accumulation of the Papillomavirus E1 Helicase Blocks S-Phase Progression and Triggers an ATM-Dependent DNA Damage Response
Nuclear Accumulation of the Papillomavirus E1 Helicase Blocks S-Phase Progression and Triggers an ATM-Dependent DNA Damage Response
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DOI：
10.1128/jvi.00542-11
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发表时间：
2011-09-01
影响因子：
5.4
通讯作者：
Archambault, Jacques
中科院分区：
文献类型：
--
作者：
Fradet-Turcotte, Amelie;Bergeron-Labrecque, Fanny;Archambault, Jacques
乳头瘤病毒基因组的复制是由病毒 E1 和 E2 蛋白之间的复合物在起点组装而启动的。 E1 解旋酶由 C 端 ATP 酶/解旋酶结构域、与起点结合的中心结构域以及包含介导其核质穿梭的核输入和输出信号的 N 端调节区组成。我们之前报道过 E1 的核积累对细胞增殖有有害影响，可以通过其核输出来阻止这种影响。在这里，我们发现来自不同乳头瘤病毒类型的 E1 的核积累会阻止早期 S 期的细胞周期进程，并以需要 E1 的起源结合和 ATP 酶活性的方式触发 DNA 损伤反应 (DDR) 和 ATM 途径的激活。与 E2 形成复合物会降低 E1 诱导 DDR 的能力，但不会阻止细胞周期停滞。短暂的病毒 DNA 复制仍然发生在 S 期停滞的细胞中，但令人惊讶的是，它既不受 DDR 和 ATM 激酶诱导的影响，也不依赖于 DDR 和 ATM 激酶的诱导。最后，我们提供的证据表明，在表达核输出缺陷的突变 E1 蛋白的人乳头瘤病毒 31 型 (HPV31) 永生化角质形成细胞中也会诱导 DDR。我们认为，E1 的核输出可防止细胞周期停滞和病毒生命周期游离维持阶段期间 DDR 的诱导，并且当 E1 在细胞核中时，与 E2 形成的复合物进一步保护未分化细胞免于经历 DDR。
Replication of the papillomavirus genome is initiated by the assembly of a complex between the viral E1 and E2 proteins at the origin. The E1 helicase is comprised of a C-terminal ATPase/helicase domain, a central domain that binds to the origin, and an N-terminal regulatory region that contains nuclear import and export signals mediating its nucleocytoplasmic shuttling. We previously reported that nuclear accumulation of E1 has a deleterious effect on cellular proliferation which can be prevented by its nuclear export. Here we have shown that nuclear accumulation of E1 from different papillomavirus types blocks cell cycle progression in early S phase and triggers the activation of a DNA damage response (DDR) and of the ATM pathway in a manner that requires both the origin-binding and ATPase activities of E1. Complex formation with E2 reduces the ability of E1 to induce a DDR but does not prevent cell cycle arrest. Transient viral DNA replication still occurs in S-phase-arrested cells but surprisingly is neither affected by nor dependent on induction of a DDR and of the ATM kinase. Finally, we provide evidence that a DDR is also induced in human papillomavirus type 31 (HPV31)-immortalized keratinocytes expressing a mutant E1 protein defective for nuclear export. We propose that nuclear export of E1 prevents cell cycle arrest and the induction of a DDR during the episomal maintenance phase of the viral life cycle and that complex formation with E2 further safeguards undifferentiated cells from undergoing a DDR when E1 is in the nucleus.