ATF3 Regulation of Histone Acetylation in Genome Maintenance

项目摘要 更好地了解DNA损伤反应(DDR)是至关重要的，因为这 进化上保守的基因组维持机制不仅是抗癌的屏障，而且 影响主要通过诱导DNA杀死癌细胞的放射治疗和化疗的疗效 损坏。尽管DNA嵌入到高度有序的染色质中，但DNA损伤会立即诱导染色质 损坏地点的改建。其中一个早期的变化是组蛋白催化的组蛋白乙酰化 乙酰转移酶Tip60和p300/CBP不仅可以促进染色质进入DNA修复机制， 但可以调节DNA修复途径的选择。由于组蛋白乙酰化已成为 协调DDR，识别在DNA损伤时调节这一事件的基因具有重要意义。 激活转录因子3(ATF3)是一种常见的由DNA损伤剂诱导的应激传感器。我们 已经证明ATF3可以激活肿瘤抑制因子P53，同时促进Tip60介导的 激活主要的DDR激酶ATM。我们还发现ATF3是基因组维持所必需的，并且 抑制小鼠自发性肿瘤的发生。鉴于这些结果支持ATF3在 在DNA损伤反应中起着不可或缺的作用，目前尚不清楚的是ATF3是否还能主动 调节染色质动力学和DNA修复，独立于其对P53和Tip60的调节。的目标是 本申请旨在解决这一问题，并确定ATF3在DNA修复调控中的作用。 染色质水平。根据令人信服的初步数据，中心假设是 DNA损伤部位的ATF3促进p300/CBP乙酰化H3，促进修复的加载 非同源末端连接蛋白(NHEJ)。为了检验这一假设，我们将确定ATF3如何 被招募到DSB，并在DSB促进p300/CBP催化的组蛋白乙酰化(目标1)。我们还将 描述ATF3调控的组蛋白乙酰化如何改变染色质结构并促进招募 NHEJ因素(目标2)。最后，我们还将使用IR诱导的淋巴肿大小鼠模型来评估 我们新发现的功能意义(目标3)。拟议研究的完成预计将确定 ATF3在基因组维持中扮演的新角色，并发现早期 染色质对DNA损伤的反应是受调控的。

Project Summary A better understanding of the DNA damage response (DDR) is of utmost importance because this evolutionally-conserved genome-maintaining mechanism not only serves as an anti-cancer barrier, but influences efficacies of radiation therapy and chemotherapy that mainly kill cancer cells by inducing DNA damage. Whereas DNA is embedded in highly-ordered chromatin, DNA damage promptly induces chromatin alterations at sites of damage. One such early change, histone acetylation catalyzed by histone acetyltransferases Tip60 and p300/CBP, not only can promote chromatin access to the DNA-repair machinery, but can regulate DNA-repair pathway choice. As histone acetylation has emerged as a principal mechanism for coordinating DDR, it is of significance to identify genes that can regulate this event upon DNA damage. Activating transcription factor 3 (ATF3) is a stress sensor commonly induced by DNA-damaging agents. We have demonstrated that ATF3 can activate the tumor suppressor p53 while promoting Tip60-mediated activation of the major DDR kinase ATM. We also found that ATF3 is required for genome maintenance and the suppression of spontaneous tumorigenesis in mice. Whereas these results support that ATF3 plays an indispensable role in the DNA damage response, what is currently unknown is whether ATF3 can also actively regulate chromatin dynamics and DNA repair independent of its regulation on p53 and Tip60. The objective of this application is to address this question, and to determine the role of ATF3 in the regulation of DNA repair at the chromatin level. Formulated on the basis of compelling preliminary data, the central hypothesis is that ATF3 recruited to sites of DNA damage promotes p300/CBP to acetylate H3 facilitating the loading of repair proteins for non-homologous end-joining (NHEJ). To test this hypothesis, we will determine how ATF3 is recruited to DSBs and promotes p300/CBP-catalyzed histone acetylation at DSBs (Aim 1). We will also delineate how histone acetylation regulated by ATF3 alters chromatin structure and facilitates the recruitments of NHEJ factors (Aim 2). Lastly, we will also use the IR-induced lymphomagenesis mouse model to assess the functional significance of our novel findings (Aim 3). Completion of the proposed research is expected to define a novel role that ATF3 plays in genome maintenance, and discover novel mechanisms by which the early chromatin response to DNA damage is regulated.