PERK inhibits DNA replication during the Unfolded Protein Response via Claspin and Chk1
PERK inhibits DNA replication during the Unfolded Protein Response via Claspin and Chk1
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DOI：
10.1038/onc.2016.239
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发表时间：
2017-02-02
期刊：
影响因子：
8
通讯作者：
Gillespie, D. A.
中科院分区：
文献类型：
--
作者：
Cabrera, E.;Hernandez-Perez, S.;Gillespie, D. A.
低氧、营养缺乏和酸化等应激干扰内质网(ER)的蛋白质折叠，并激活未折叠蛋白质反应(UPR)，通过PERK、IRE1和ATF6效应器触发适应性反应。大多数反应与内质网稳态有关；然而，在这里，我们表明UPR的PERK分支也控制DNA复制。用非遗传毒性的UPR激动剂thapsigargin处理细胞后，DNA合成迅速受到抑制，这可归因于DNA复制叉慢和复制起点激发减少的组合。DNA合成抑制依赖于UPR效应器PERK，并与检查点适配器蛋白Claspin的磷酸化和Chk1效应器激酶的激活有关，这两种情况都发生在没有可检测到DNA损伤的情况下。值得注意的是，thapsigargin不会抑制大量DNA合成，也不会在缺乏Claspin的细胞中激活Chk1，或者当Chk1耗尽或受到化学抑制时。在每一种情况下，thapsigargin抗性的DNA合成都是由于复制起点激发的增加，从而补偿了分叉进展的减少。综上所述，我们的结果揭示了Perk功能的一个新方面，以及在没有遗传毒性应激的情况下，Claspin和Chk1作为DNA复制的负调节因子所扮演的未知角色。由于肿瘤细胞在次优环境中增殖，并且经常显示UPR激活的证据，这一途径可以调节对DNA复制靶向化疗的反应。
Stresses such as hypoxia, nutrient deprivation and acidification disturb protein folding in the endoplasmic reticulum (ER) and activate the Unfolded Protein Response (UPR) to trigger adaptive responses through the effectors, PERK, IRE1 and ATF6. Most of these responses relate to ER homoeostasis; however, here we show that the PERK branch of the UPR also controls DNA replication. Treatment of cells with the non-genotoxic UPR agonist thapsigargin led to a rapid inhibition of DNA synthesis that was attributable to a combination of DNA replication fork slowing and reduced replication origin firing. DNA synthesis inhibition was dependent on the UPR effector PERK and was associated with phosphorylation of the checkpoint adaptor protein Claspin and activation of the Chk1 effector kinase, both of which occurred in the absence of detectable DNA damage. Remarkably, thapsigargin did not inhibit bulk DNA synthesis or activate Chk1 in cells depleted of Claspin, or when Chk1 was depleted or subject to chemical inhibition. In each case thapsigargin-resistant DNA synthesis was due to an increase in replication origin firing that compensated for reduced fork progression. Taken together, our results unveil a new aspect of PERK function and previously unknown roles for Claspin and Chk1 as negative regulators of DNA replication in the absence of genotoxic stress. Because tumour cells proliferate in suboptimal environments, and frequently show evidence of UPR activation, this pathway could modulate the response to DNA replication-targeted chemotherapies.