Mechanisms of EXO1 regulation in response to radiation-induced DNA damage

EXO1 响应辐射引起的 DNA 损伤的调节机制

• 批准号: 9926813
• 负责人: Sandeep Burma
• 金额: $ 30.49万
• 依托单位: UNIVERSITY OF TEXAS HLTH SCIENCE CENTER
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-11-28 至 2022-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9926813
• 关键词: Back; Binding; Cell Cycle; Cell Survival; Cells; Clinical Trials; Complex; DNA; DNA Damage; DNA Double Strand Break; DNA Repair; Double Strand Break Repair; EXO1 gene; Enzymes; Event; Excision; Exercise; G2 Phase; Genomic Instability; Genomics; Goals; Human; In Vitro; Ionizing radiation; Lesion; Maintenance; Malignant - descriptor; Malignant Neoplasms; Modification; Molecular; Nonhomologous DNA End Joining; Pathway interactions; Phase; Phosphorylation; Play; Post-Translational Protein Processing; Process; Proteins; Publishing; Radiation; Radiation Induced DNA Damage; Radiation therapy; Radiosensitization; Regimen; Regulation; Research; Resistance; Role; S Phase; Site; Testing; Therapeutic; Ubiquitin; Ubiquitination; Work; base; cancer cell; cancer therapy; experimental study; genome integrity; homologous recombination; in vivo; inhibitor/antagonist; novel; preservation; prevent; public health relevance; radiation response; recruit; repaired; response; spleen exonuclease

 DESCRIPTION (provided by applicant): Ionizing radiation (IR) remains one of the mainstays of cancer therapy. The most deleterious lesion induced by IR is the DNA double-strand break (DSB). Accurate repair of DSBs is essential for preventing loss of genomic integrity and malignant transformation. Efficient repair of DSBs also underlies the resistance of many cancers to radiation therapy. A cell must choose between two major repair pathways to fix these breaks - non- homologous end joining (NHEJ), an error-prone pathway that is operative in all phases of the cell cycle or homologous recombination (HR), an error-free pathway that is restricted to the post-replicative phases of the cell cycle. Optimal usage of these two pathways is vital for the maintenance of genomic integrity and cell survival in the face of genomic insults. The DNA end resection step of HR is a pivotal point at which correct repair pathway choice is exercised. Importantly, research from our lab and others has established that the 5' to 3' exonuclease EXO1 is a critical player in DNA end resection and repair pathway choice in human cells. While DNA end resection is currently an avidly researched topic in the field of DNA repair, the exact sequence of molecular events involving EXO1 that allows commitment to a particular repair pathway is not well worked out. Exciting new results from our lab demonstrate that EXO1 is phosphorylated by CDKs 1/2 in a cell cycle- dependent manner and by ATM/ATR in a DNA damage-dependent manner to promote DNA end resection. However, soon after DNA damage, EXO1 is SUMOylated, ubiquitinated, and rapidly targeted for degradation, presumably to prevent uncontrolled resection of DNA ends. It is important to mechanistically understand how these and other post translational modifications stimulate or restrain EXO1's functions in the cellular response to IR. Towards this goal, we propose to develop a comprehensive picture of cell cycle- and IR-dependent modifications and interacting partners of EXO1, and to mechanistically understand how these modifications promote EXO1 activation and subsequent degradation in response to IR. Based upon our preliminary results, we hypothesize that EXO1 activation and inactivation is a tightly controlled process involving phosphorylation, SUMOylation and ubiquitination events that fine-tune DNA end resection, optimize DSB repair, and preserve genomic integrity. Understanding the sequence and functions of EXO1 post- translational modifications and the exact choreography of EXO1 and its interacting partners at DSBs will be of paramount importance in developing more effective radiosensitization approaches that target the critical DNA end resection step. Specifically, we propose to: 1) Test the hypothesis that phosphorylation of EXO1 by CDKs and PI3KKs regulates DNA end resection and influences repair pathway choice, 2) Test the hypothesis that EXO1 degradation post-radiation restrains DNA end resection and preserves genomic integrity, and 3) Test the hypothesis that blocking EXO1 activation with CDK 1/2 inhibitors may be a viable strategy for therapeutically sensitizing cancers to ionizing radiation.

 描述（由适用提供）：电离辐射（IR）仍然是癌症疗法的主要支柱之一。 IR诱导的最删除的病变是DNA双链断裂（DSB）。 DSB的准确修复对于防止基因组完整性和恶性转化的丧失至关重要。 DSB的有效修复还基于许多癌症对放射治疗的抗性。一个单元必须在两个主要的修复途径之间进行选择以固定这些断裂 - 非同源末端连接（NHEJ），这是一种在细胞周期的所有阶段或同源重组（HR）的所有阶段运行的途径（HR），这是一种限制在细胞周期复制阶段的无错误途径。面对基因组损伤，这两种途径的最佳用法对于维持基因组完整性和细胞存活至关重要。人力资源的DNA末端切除步骤是一个关键点，正确的修复途径选择令人兴奋。重要的是，我们实验室和其他人的研究表明，5'至3'外切核酸酶Exo1是人类细胞中DNA终端切除和修复途径选择的关键参与者。尽管DNA终端切除术当前是DNA修复领域中经过广泛研究的主题，但涉及EXO1的分子事件的确切序列允许对特定修复途径进行承诺。我们实验室的令人兴奋的新结果表明，exo1以细胞周期不同的方式被CDKS 1/2磷酸化，并以DNA损伤依赖性方式通过ATM/ATR磷酸化，以促进DNA终端切除。然而，在DNA损伤后不久，Exo1被征服，泛素化并迅速降级，大概是为了防止DNA末端的不受控制的切除。重要的是要机械理解这些转化后的修饰如何刺激或抑制EXO1在细胞对IR的响应中的功能。为了实现这一目标，我们建议对EXO1的细胞周期和IR依赖性修饰以及相互作用的伴侣进行全面了解，并机械地了解这些修饰如何促进Exo1激活以及随后响应IR的降解。基于我们的初步结果，我们假设exo1激活和灭活是一个紧密控制的过程，涉及磷酸化，sumoylation和泛素化事件，可微调DNA末端切除，优化DSB修复并保留基因组完整性。了解EXO1翻译后修饰的序列和功能以及DSBS上的Exo1及其相互作用伙伴的确切编排对于开发针对关键DNA终端切除步骤的更有效的放射敏化方法至关重要。 Specifically, we propose to: 1) Test the hypothesis that phosphorylation of EXO1 by CDKs and PI3KKs regulates DNA end resection and influences repair pathway choice, 2) Test the hypothesis that EXO1 degradation post-radiation restrains DNA end resection and preserves genomic integrity, and 3) Test the hypothesis that blocking EXO1 activation with CDK 1/2 inhibitors may be a viable strategy用于治疗化癌症对电离辐射的敏感性。

项目成果

A TNF-JNK-Axl-ERK signaling axis mediates primary resistance to EGFR inhibition in glioblastoma.

• DOI: 10.1038/nn.4584
• 发表时间: 2017-08
• 期刊: Nature neuroscience
• 影响因子: 25
• 作者: Guo G;Gong K;Ali S;Ali N;Shallwani S;Hatanpaa KJ;Pan E;Mickey B;Burma S;Wang DH;Kesari S;Sarkaria JN;Zhao D;Habib AA
• 通讯作者: Habib AA

MET signaling promotes DNA repair and radiation resistance in glioblastoma stem-like cells.

• DOI: 10.21037/atm.2017.01.67
• 发表时间: 2017-02
• 期刊: Annals of translational medicine
• 作者: P. Todorova;B. Mukherjee;S. Burma

EEPD1 promotes repair of oxidatively-stressed replication forks.

• DOI: 10.1093/narcan/zcac044
• 发表时间: 2023-03
• 期刊: NAR cancer
• 影响因子: 5.1

Endonuclease EEPD1 Is a Gatekeeper for Repair of Stressed Replication Forks.

• DOI: 10.1074/jbc.m116.758235
• 发表时间: 2017-02-17
• 期刊: The Journal of biological chemistry
• 作者: Kim HS;Nickoloff JA;Wu Y;Williamson EA;Sidhu GS;Reinert BL;Jaiswal AS;Srinivasan G;Patel B;Kong K;Burma S;Lee SH;Hromas RA
• 通讯作者: Hromas RA

Enhanced dependency of KRAS-mutant colorectal cancer cells on RAD51-dependent homologous recombination repair identified from genetic interactions in Saccharomyces cerevisiae.

• DOI: 10.1002/1878-0261.12040
• 发表时间: 2017-05
• 期刊: Molecular oncology
• 影响因子: 6.6
• 作者: Kalimutho M;Bain AL;Mukherjee B;Nag P;Nanayakkara DM;Harten SK;Harris JL;Subramanian GN;Sinha D;Shirasawa S;Srihari S;Burma S;Khanna KK
• 通讯作者: Khanna KK