The role of DNA polymerase eta in DNA damage response and p53 activation

描述（由申请人提供）：DNA聚合酶eta在DNA损伤反应和p53激活中的作用。本申请旨在研究DNA聚合酶eta （PolH）在DNA损伤反应和p53激活中的信号通路，以及p53与PolH信号通路相互作用对细胞生存和死亡的影响。为了描述p53在DNA损伤反应中的作用，我们发现DNA损伤可以以p53依赖的方式诱导PolH。PolH是色素干皮病（XP）基因的产物。XP是一种常染色体隐性遗传病，XP患者易发生恶性皮肤癌的早发性。有趣的是，我们发现敲低PolH通过抑制DNA损伤诱导的细胞凋亡来提高细胞存活率。我们还发现，DNA损伤诱导的p53激活在PolH-敲低和PolH-缺失的细胞中都受到损害，这可以通过重组的PolH来挽救。此外，我们发现PolH通过ATM- ChK2-p53通路调节DNA损伤反应。最后，我们最近的初步研究表明，当DNA损伤时，PolH蛋白的稳定性降低，PolH与Mdm2和Pirh2物理相互作用，两者都是p53的靶基因和E3连接酶。综上所述，我们假设PolH活性受多种途径调控，PolH在DNA损伤反应和p53激活中具有新的功能。为了进一步解决这一问题，提出了以下三个具体目标：(1)确定PolH表达是否以及如何在基础和DNA损伤条件下受到调节；(2)确定PolH与Mdm2或Pirh2相互作用的功能意义；(3)确定PolH在DNA损伤反应和p53激活中的作用。

DESCRIPTION (provided by applicant): The role of DNA polymerase eta in DNA damage response and p53 activation. This application is proposed to address the signaling pathway of DNA polymerase eta (PolH) in DNA damage response and p53 activation and the effect of the signal pathway interaction between p53 and PolH on cell survival and death. In an effort to characterize the role of p53 in DNA damage response, we found that PolH can be induced by DNA damage in a p53-dependent manner. PolH is the product of the Xeroderma Pigmentosum (XP) gene. XP is an autosomal recessive disorder, and XP patients are prone to early onset of malignant skin cancers. Interestingly, we found that knockdown of PolH enhances cell survival by inhibiting DNA damage-induced apoptosis. We also found that DNA damage-induced activation of p53 is impaired in both PolH-knockdown and PolH-null cells, which can be rescued by a reconstituted PolH. Furthermore, we found that PolH modulates DNA damage response via the ATM- ChK2-p53 pathway. Finally, our recent preliminary studies showed that the stability of PolH protein is decreased upon DNA damage and PolH physically interacts with Mdm2 and Pirh2, both of which are a p53 target gene and an E3 ligase. Taken together, we hypothesize that PolH activity is regulated by multiple pathways and PolH has novel functions in DNA damage response and p53 activation. To further address this, the following three specific aims are proposed: (1) to determine whether and how PolH expression is regulated at basal and DNA damage conditions; (2) to determine the functional significance of the interaction between PolH and Mdm2 or Pirh2; and (3) to determine the role of PolH in DNA damage response and p53 activation.