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

DNA聚合酶eta在DNA损伤反应和p53激活中的作用

• 批准号: 7898966
• 负责人: Xinbin Chen
• 金额: $ 28.57万
• 依托单位: UNIVERSITY OF CALIFORNIA AT DAVIS
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-04-01 至 2015-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7898966
• 关键词: Address; Apoptosis; Bypass; Carcinogens; Cell Survival; Cells; Cessation of life; DNA Damage; DNA biosynthesis; DNA lesion; DNA-Directed DNA Polymerase; Degradation Pathway; Development; Disease; Double Strand Break Repair; Exhibits; Family; Frequencies; Gene Targeting; Genes; Genomic Instability; Lead; Lesion; Malignant - descriptor; Malignant Neoplasms; Modification; Mono-S; Nucleotide Excision Repair; Null Lymphocytes; Pathway interactions; Patients; Play; Protein p53; Proteins; Pyrimidine Dimers; Rad30 protein; Role; Signal Pathway; Sister Chromatid Exchange; Skin Cancer; TP53 gene; Treatment Efficacy; Tumor Suppressor Proteins; UV induced; Ubiquitination; Variant; Xeroderma Pigmentosum; early onset; homologous recombination; novel; prevent; public health relevance; reconstitution; repaired; response; tumor initiation; ubiquitin-protein ligase; ultraviolet irradiation

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. PUBLIC HEALTH RELEVANCE: It is well-known that loss of p53 tumor suppressor leads to genome instability and Xeroderma Pigmentosum (XP) patients often exhibit a high frequency of genome instability. In addition, the magnitude of genome instability is much higher in cells lacking both Xeroderma Pigmentosum (XP) and p53 genes than cells lacking either one individually. Interestingly, we found that PolH, the XPV gene product, is a novel p53 target gene and knockdown of PolH enhances cell survival by inhibiting DNA damage-induced apoptosis. Surprisingly, we found that activation of p53 following DNA damage is impaired in both PolH-knockdown and PolH-null cells, which can be rescued by reconstituted PolH. Given the fact that loss of PolH predisposes XP patients to early onset of multiple malignant skin cancers and that p53 is a tumor suppressor, further studies to address how PolH modulates p53 activation and DNA damage response are highly significant and warranted.

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。 该申请旨在解决 DNA 损伤反应和 p53 激活中 DNA 聚合酶 eta (PolH) 的信号通路以及 p53 和 PolH 之间的信号通路相互作用对细胞存活和死亡的影响。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 依赖性方式诱导 PolH。 PolH 是色素性干皮病 (XP) 基因的产物。 XP是一种常染色体隐性遗传病，XP患者容易早期发生恶性皮肤癌。有趣的是，我们发现敲除 PolH 可通过抑制 DNA 损伤诱导的细胞凋亡来增强细胞存活率。我们还发现，DNA 损伤诱导的 p53 激活在 PolH 敲低和 PolH 无效细胞中均受到损害，这可以通过重建 PolH 来挽救。此外，我们发现 PolH 通过 ATM-ChK2-p53 途径调节 DNA 损伤反应。最后，我们最近的初步研究表明，DNA 损伤后 PolH 蛋白的稳定性降低，并且 PolH 与 Mdm2 和 Pirh2（两者都是 p53 靶基因和 E3 连接酶）发生物理相互作用。综上所述，我们假设 PolH 活性受到多种途径的调节，并且 PolH 在 DNA 损伤反应和 p53 激活中具有新的功能。为了进一步解决这个问题，提出了以下三个具体目标：（1）确定PolH表达在基础和DNA损伤条件下是否以及如何受到调节； (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。 公共健康相关性：众所周知，p53 肿瘤抑制因子的缺失会导致基因组不稳定，色素性干皮病 (XP) 患者经常表现出高频率的基因组不稳定。此外，同时缺乏色素干皮病 (XP) 和 p53 基因的细胞中基因组不稳定性的程度比单独缺乏其中任何一种基因的细胞要高得多。有趣的是，我们发现 XPV 基因产物 PolH 是一种新型 p53 靶基因，敲低 PolH 可通过抑制 DNA 损伤诱导的细胞凋亡来增强细胞存活率。令人惊讶的是，我们发现 DNA 损伤后 p53 的激活在 PolH 敲低和 PolH 无效细胞中均受到损害，这可以通过重建 PolH 来挽救。鉴于 PolH 的缺失使 XP 患者容易患上多种恶性皮肤癌，并且 p53 是一种肿瘤抑制因子，因此进一步研究 PolH 如何调节 p53 激活和 DNA 损伤反应是非常重要和必要的。