ATF2 in DNA damage response.

ATF2 在 DNA 损伤反应中的作用。

• 批准号: 7014962
• 负责人: Ze'ev A Ronai
• 金额: $ 47.06万
• 依托单位: SANFORD BURNHAM PREBYS MEDICAL DISCOVERY INSTITUTE
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-09-19 至 2011-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7014962
• 关键词: DNA damage; cell cycle; histones; melanoma; mutant; neoplasm /cancer; phosphorylation; proteins

DESCRIPTION (provided by applicant): The transcription factor ATF2 contributes to cell cycle and cell death decisions upon its phosphorylation by stress kinases. We recently discovered that ATM phosphorylates ATF2 on Ser490/8 following the formation of double-stranded DNA breaks (DSBs) by ionizing radiation (IR). Consequently, ATF2 is rapidly recruited to DSB-induced foci, where it co-localizes with gamma-H2AX as well as with DNA repair proteins such as Mre11, Rad50 and NBS1 (MRN). Inhibition of ATF2 expression impairs recruitment of Mre11 and NBS1 to the repair foci and attenuates the S-phase checkpoint, and results in hypersensitivity to IR. Furthermore, ATF2 is also required for the activation of ATM, and consequently of Chk1 and Chk2. Significantly, the newly identified role of ATF2 in DNA damage response does not require its transcriptional activity. These findings provide the foundation for our hypothesis that via distinct regulatory pathways (ATM vs. JNK/p38) ATF2 contributes to separate cellular functions: transcription,and DNA damage response and consequently, tumorigenesis. We will test this hypothesis by characterizing the requirements and the mechanism(s) underlying the newly identified function of ATF2 as a regulator of the DNA damage response as it pertains to normal cellular growth and tumorigenesis. Specifically we will: (1) Characterize ATF2 as a regulator of DNA damage in the context of histone modification and ATM activation. Earlier studies established ATF2 association with components of TIP60 histone acetyltransferase complex; ATF2 homologues in S. pombe are implicated in chromatin remodeling, which is now linked with the activation of ATM. We will characterize the role of ATF2 in histone acetylation and the induction of ATM in response to DSB; (2) Utilize fission yeast as a model to genetically dissect ATF2 homolog (Atf21, Pcr1) functions in DNA damage responses. Fission yeast has long provided a paradigm for cell cycle control and DNA damage responses. The stress signaling molecules, including ATF2, are conserved in this organism, and its genetic simplicity will be utilized to independently further develop our preliminary data and to act as a genetic model to test chromatin modifications in a well defined and controlled setting; (3) Determine the effect of p38/JNK on ATM phosphorylation of ATF2 (and vice versa) in relation to ATF2 activity in transcription and the DNA damage response in non-transformed and in tumor cells; (4) Assess which of ATF2 modifications and functions (transcription/damage response) is required for its regulation of the cell cycle, growth control, apoptosis, and tumorigenicity in non transformed and in melanoma cell lines; (5) Determine changes in the skin and melanoma tumor formation and in rate of mutagenesis in mice expressing transcriptional or ATM-mutant forms of ATF2. Overall, using the powerful genetics of S. Pombe, the relevant mammalian cell cultures combined with genetic mouse models our proposal will provide important new understanding of ATF2 in transcription and DNA damage response.

描述（由申请人提供）：转录因子ATF2通过应激激酶磷酸化参与细胞周期和细胞死亡决定。我们最近发现，在电离辐射（IR）形成双链DNA断裂（DSBs）后，ATM使ATF2的Ser490/8磷酸化。因此，ATF2被迅速招募到dsb诱导的病灶，在那里它与γ - h2ax以及DNA修复蛋白如Mre11、Rad50和NBS1 （MRN）共定位。抑制ATF2表达会损害Mre11和NBS1向修复病灶的募集，减弱s期检查点，并导致对IR的超敏反应。此外，ATF2也是ATM激活所必需的，因此也是Chk1和Chk2的激活所必需的。值得注意的是，新发现的ATF2在DNA损伤应答中的作用并不需要其转录活性。这些发现为我们的假设提供了基础，即通过不同的调控途径（ATM与JNK/p38）， ATF2有助于不同的细胞功能：转录，DNA损伤反应，从而促进肿瘤发生。我们将通过描述新发现的ATF2作为DNA损伤反应调节器的功能的要求和机制来验证这一假设，因为它与正常细胞生长和肿瘤发生有关。具体来说，我们将：(1)将ATF2描述为组蛋白修饰和ATM激活背景下DNA损伤的调节剂。早期的研究证实了ATF2与TIP60组蛋白乙酰转移酶复合物组分的关联；S. pombe中的ATF2同源物与染色质重塑有关，这现在与ATM的激活有关。我们将描述ATF2在组蛋白乙酰化和诱导ATM响应DSB中的作用；(2)以裂变酵母为模型，从基因上解剖ATF2同源物（Atf21, Pcr1）在DNA损伤反应中的功能。裂变酵母长期以来为细胞周期控制和DNA损伤反应提供了一个范例。应激信号分子，包括ATF2，在这种生物体中是保守的，其遗传简单性将被用来独立地进一步发展我们的初步数据，并作为一个遗传模型，在一个明确和可控的环境中测试染色质修饰；(3)确定p38/JNK对ATF2的ATM磷酸化的影响（反之亦然），以及与非转化细胞和肿瘤细胞中ATF2转录活性和DNA损伤反应的关系；(4)评估哪些ATF2修饰和功能（转录/损伤反应）是其在非转化和黑色素瘤细胞系中调节细胞周期、生长控制、凋亡和致瘤性所必需的；(5)确定表达ATF2转录或atm突变形式的小鼠皮肤和黑色素瘤形成的变化以及诱变率。总之，利用S. Pombe的强大遗传学，相关哺乳动物细胞培养结合遗传小鼠模型，我们的建议将为ATF2在转录和DNA损伤反应中的作用提供重要的新认识。