Regulation of Ionizing Radiation Induced DNA Damage Response

电离辐射诱导的 DNA 损伤反应的调节

• 批准号: 8444597
• 负责人: Xiaochun Yu
• 金额: $ 28.12万
• 依托单位: UNIVERSITY OF MICHIGAN AT ANN ARBOR
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-05-01 至 2014-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8444597
• 关键词: BRCA1 gene; Binding; Cancer-Predisposing Gene; Cell Cycle Progression; Cells; Chromatin; DNA; DNA Damage; DNA Repair; DNA damage checkpoint; Data; FHA Domain; Functional disorder; Genome Stability; Genomics; Growth; Histone H4; Histones; Incidence; Ionizing radiation; Knockout Mice; Maintenance; Methylation; Molecular; Monitor; Mono-S; Mus; Pathway interactions; Phenotype; Phosphotransferases; Play; Prevention; Proteins; Radiation Induced DNA Damage; Regulation; Ring Finger Domain; Risk; Role; Scaffolding Protein; Signal Transduction; Site; Sterility; Time; Tumor Suppression; Tumor Suppressor Proteins; Ubiquitination; base; cancer cell; hazard; human 53BP1 protein; human H2AX protein; in vivo; insight; male; malignant breast neoplasm; public health relevance; research study; response; tumor; tumorigenesis; ubiquitin-protein ligase

DESCRIPTION (provided by applicant): Ionizing radiation induces DNA double stand breaks, which activates a signal cascade initiated by ATM/ATR kinases. The damage signals stop the cell cycle progression and allow enough time for DNA damage repair. Here, we have identified an important regulator, RNF8 (Ring Finger protein 8) that participates in the activation of DNA damage response. Following DNA damage, the FHA domain of RNF8 recognizes phosphorylated MDC1, a binding partner of histone H2AX in DNA damage response, which targets RNF8 to DNA damage sites. Histone H2AX is a scaffold protein that retains DNA damage response proteins at the DNA damage sites. Since RNF8 is an E3 ubiquitin ligase, we have found that RNF8 controls histone H2AX ubiquitination following DNA damage. RNF8-dependent H2AX ubiquitination may regulate downstream 53BP1 (p53 Binding Protein 1) and BRCA1 (Breast Cancer Susceptibility Gene 1) translocation to DNA damage sites. Both BRCA1 and 53BP1 are not only downstream targets of ATM/ATR kinases, but also important tumor suppressors. Moreover, we have generated RNF8 knock-out mice. The RNF8 null mice are viable. But male RNF8 -/- mice are sterile. RNF8 -/- mice are hypersensitive to ionizing radiation. These phenotypes are very similar to those of histone H2AX and MDC1 knock-out mice. Thus, based on our preliminary studies, we hypothesize that RNF8 plays a major role in activation of DNA damage response and participates in tumor prevention. We propose following experiments to examine our hypotheses. Aim1: To investigate the role of RNF8-dependent histone ubiquitination in DNA damage response. Aim2: To study the role of RNF8 in histone methylation in response to DNA damage. Aim3: To examine the role of RNF8 in tumor suppression. In summary, our proposed studies will not only provide insights into the mechanisms of the activation of DNA damage response, but also contribute to our understanding of the maintenance of genomic integrity and tumor prevention.

描述（由申请人提供）： 电离辐射会诱导 DNA 双链断裂，从而激活 ATM/ATR 激酶引发的信号级联。损伤信号会阻止细胞周期进程，并为 DNA 损伤修复留出足够的时间。在这里，我们发现了一个重要的调节因子 RNF8（环指蛋白 8），它参与 DNA 损伤反应的激活。 DNA 损伤后，RNF8 的 FHA 结构域识别磷酸化的 MDC1，MDC1 是 DNA 损伤反应中组蛋白 H2AX 的结合伴侣，将 RNF8 靶向 DNA 损伤位点。组蛋白 H2AX 是一种支架蛋白，可在 DNA 损伤位点保留 DNA 损伤反应蛋白。由于 RNF8 是一种 E3 泛素连接酶，我们发现 RNF8 在 DNA 损伤后控制组蛋白 H2AX 泛素化。 RNF8 依赖性 H2AX 泛素化可能调节下游 53BP1（p53 结合蛋白 1）和 BRCA1（乳腺癌易感基因 1）易位至 DNA 损伤位点。 BRCA1和53BP1不仅是ATM/ATR激酶的下游靶点，也是重要的肿瘤抑制因子。此外，我们还培育出了 RNF8 基因敲除小鼠。 RNF8 缺失小鼠是可存活的。但雄性 RNF8 -/- 小鼠是不育的。 RNF8 -/- 小鼠对电离辐射过敏。这些表型与组蛋白 H2AX 和 MDC1 敲除小鼠的表型非常相似。因此，根据我们的初步研究，我们假设RNF8在DNA损伤反应的激活中起主要作用并参与肿瘤预防。我们建议进行以下实验来检验我们的假设。目的1：研究RNF8依赖性组蛋白泛素化在DNA损伤反应中的作用。目的2：研究RNF8在组蛋白甲基化响应DNA损伤中的作用。目的3：检查RNF8在肿瘤抑制中的作用。总之，我们提出的研究不仅将深入了解 DNA 损伤反应的激活机制，而且有助于我们理解基因组完整性的维持和肿瘤预防。