ATR phosphorylates SMARCAL1 to prevent replication fork collapse
ATR phosphorylates SMARCAL1 to prevent replication fork collapse
复制标题
DOI：
10.1101/gad.214080.113
复制
发表时间：
2013-07-15
影响因子：
10.5
通讯作者：
Cortez, David
中科院分区：
文献类型：
--
作者：
Couch, Frank B.;Bansbach, Carol E.;Cortez, David
DNA损伤反应激酶共济失调毛细血管扩张和Rad 3相关（ATR）协调许多细胞对复制应激的反应。ATR在复制应激条件下调节DNA合成的确切机制在很大程度上是未知的，但这种活性对癌细胞的生存力和增殖至关重要，使ATR成为潜在的治疗靶点。在这里，我们使用选择性ATR抑制剂，以证明ATR激酶活性的急性抑制产生快速的细胞致死性，破坏复制起始的时间，减慢复制延长，并诱导叉崩溃。我们定义了这种分叉崩溃的机制，包括SLX 4依赖性切割产生双链断裂和CtIP依赖性切除产生过量的单链模板和新生DNA链。我们的数据表明，这些核酸酶的DNA底物至少部分由SMARCAL 1 DNA移位酶产生。适当调节SMARCAL 1促进停滞的叉修复和重新启动;然而，当ATR在哺乳动物和爪蟾系统中失活时，不受调节的SMARCAL 1有助于叉崩溃。ATR使S652上的SMARCAL 1磷酸化，从而限制其分叉退化活动并防止异常分叉处理。因此，SMARCAL 1的磷酸化是ATR防止分叉崩溃、促进DNA复制完成和维持基因组完整性的一种机制。
The DNA damage response kinase ataxia telangiectasia and Rad3-related (ATR) coordinates much of the cellular response to replication stress. The exact mechanisms by which ATR regulates DNA synthesis in conditions of replication stress are largely unknown, but this activity is critical for the viability and proliferation of cancer cells, making ATR a potential therapeutic target. Here we use selective ATR inhibitors to demonstrate that acute inhibition of ATR kinase activity yields rapid cell lethality, disrupts the timing of replication initiation, slows replication elongation, and induces fork collapse. We define the mechanism of this fork collapse, which includes SLX4-dependent cleavage yielding double-strand breaks and CtIP-dependent resection generating excess single-stranded template and nascent DNA strands. Our data suggest that the DNA substrates of these nucleases are generated at least in part by the SMARCAL1 DNA translocase. Properly regulated SMARCAL1 promotes stalled fork repair and restart; however, unregulated SMARCAL1 contributes to fork collapse when ATR is inactivated in both mammalian and Xenopus systems. ATR phosphorylates SMARCAL1 on S652, thereby limiting its fork regression activities and preventing aberrant fork processing. Thus, phosphorylation of SMARCAL1 is one mechanism by which ATR prevents fork collapse, promotes the completion of DNA replication, and maintains genome integrity.