Functions of SAMHD1 in DNA Double-strand Break Repair

SAMHD1在DNA双链断裂修复中的功能

• 批准号: 9192739
• 负责人: Waaqo Boru Daddacha
• 金额: $ 5.61万
• 依托单位: EMORY UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-01 至 2017-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9192739
• 关键词: Acquired Immunodeficiency Syndrome; Biochemical; Biological; Biological Markers; Cells; Chronic Lymphocytic Leukemia; Clinical; Co-Immunoprecipitations; Critical Pathways; DNA; DNA Damage; DNA Double Strand Break; Data; Diagnostic; Disease; Double Strand Break Repair; Excision; Exonuclease; Genetic; Genetic Recombination; HIV-1; In Vitro; Infection; Ionizing radiation; Malignant Neoplasms; Mediating; Mediator of activation protein; Mutation; Nonhomologous DNA End Joining; Nucleotides; Pathway interactions; Phosphorylation; Play; Post-Translational Protein Processing; Proteins; Recruitment Activity; Reporter; Resistance; Reverse Transcription; Role; SAM Domain; Site; System; Testing; Therapeutic; XRCC5 gene; base; cancer cell; cancer therapy; chemotherapy; genome integrity; homologous recombination; in vivo; inhibitor/antagonist; insight; novel; nuclease; p53-binding protein 1; prevent; protein protein interaction; pseudotoxoplasmosis syndrome; repaired; research study; response; tool

PROJECT SUMMARY DNA double strand breaks (DSBs) are potentially catastrophic cellular insults that must be recognized and repaired to maintain genome integrity. DSB repair (DSBR) depends on two complicated and highly coordinated pathways: non-homologous end joining (NHEJ), which is error prone, and homology recombination (HR), which is error free. DNA DSB end resection initiates HR and is a critical determinant of DNA DSB repair pathway choice; however, the precise mechanisms by which DNA DSB repair is regulated are still not well understood. Due to the role of DNA DSB repair in mediating resistance to many types of cancer treatments, including cancer ionizing radiation (IR) and chemotherapy, elucidating how cells direct the repair of DNA DSBs also has significant clinical implications for developing better diagnostic and/or therapeutic tools. Here, a novel role for SAM domain and HD domain 1 (SAMHD1) in DNA DSBR is shown. Mutations in SAMHD1 are associated with AIDS, (AGS), and (CLL). SAMHD1 possesses both dNTP triphosphohydrolase (dNTPase) and exonuclease activities. Its dNTPase activity is well established and has a role in restricting HIV-1 replication by depleting nucleotides required for reverse transcription. However, how SAMHD1 functions as a nuclease is not well understood. Preliminary data show that, in response to DNA damage, SAMHD1 forms foci at DNA damage sites and that SAMHD1 interacts with known DSBR proteins. Depletion of SAMHD1 in cells impairs DNA end resection and HR. Interestingly, depletion of SAMHD1 sensitizes cells to IR and PARP inhibitor, further suggesting its role in DSBR, but mediates resistance to HU treatment, suggesting that SAMHD1 may function as a critical mediator of resistance to distinct types of DNA damaging agents. The hypothesis being tested is that SAMHD1 maintains genome integrity in response to DNA DSBs at least in part by promoting homologous recombination through DNA end resection. Furthermore, SAMHD1 through its unique combination of exonuclease and dNTPase activities may play a critical role in discriminating resistance to IR and chemotherapy, which may be exploited for cancer therapy. To test this hypothesis, following specific aims are proposed: 1) Determine the mechanism by which SAMHD1 functions in DNA DSB repair; 2) Delineate the mechanism by which SAMHD1 is regulated in DNA DSB repair; 3) Determine the extent to which SAMHD1 functions as a biomarker for discriminating DNA damage sensitivity. These aims will be completed by a combination of cell biological, genetic, and biochemical approaches. Completion of these aims will provide novel insights into how SAMHD1 maintains genome integrity by promoting HR and prevents disease, including AGS, CLL, and HIV1 infection. Moreover, given the unique ability of SAMHD1 to regulate cellular dNTP pools and metabolize DNA, SAMHD1 may also function as an important biomarker for discriminating resistance of cancer cells to different types of cancer therapies that induce DNA damage, including chemotherapy and IR. Aicardi-Goutières syndrome chronic lymphocytic leukemia

项目摘要 DNA双链断裂（DSB）是一种潜在的灾难性细胞损伤，必须加以识别 并修复以保持基因组的完整性。DSB修复（DSBR）取决于两个复杂且高度复杂的过程。 协调途径：非同源末端连接（NHEJ），这是容易出错的，和同源性 重组（HR），其是无错误的。DNA DSB末端切除启动HR，并且是HR的关键决定因素。 DNA DSB修复途径的选择;然而，DNA DSB修复调节的精确机制是 仍然没有很好地理解。由于DNA DSB修复在介导对许多类型癌症的抗性中的作用， 治疗，包括癌症电离辐射（IR）和化疗，阐明细胞如何指导修复 DNA DSB对于开发更好的诊断和/或治疗工具也具有重要的临床意义。 在这里，SAM结构域和HD结构域1（SAMHD 1）在DNA DSBR中的新作用被显示。突变 SAMHD 1与艾滋病（AGS）相关， （CLL）。SAMHD 1具有dNTP三磷酸水解酶（dNTP triphosphohydrolase，dNTH）和核酸外切酶活性。其 dNTR活性已被充分确立，并通过消耗核苷酸在限制HIV-1复制中发挥作用 需要逆转录。然而，SAMHD 1如何作为核酸酶发挥作用还不清楚。 初步数据显示，响应于DNA损伤，SAMHD 1在DNA损伤位点形成灶， SAMHD 1与已知的DSBR蛋白相互作用。细胞中SAMHD 1的消耗损害DNA末端切除， HR.有趣的是，SAMHD 1的缺失使细胞对IR和PARP抑制剂敏感，进一步表明其在免疫抑制中的作用。 DSBR，但介导对HU处理的抗性，表明SAMHD 1可能作为关键介导剂发挥作用 对不同类型的DNA损伤剂的抵抗力。正在测试的假设是，SAMHD 1 至少部分地通过促进同源重组来维持基因组完整性以响应DNA DSB 通过DNA末端切除。此外，SAMHD 1通过其独特的核酸外切酶和 dNTR活性可能在鉴别IR和化疗耐药中起关键作用，这可能是 用于癌症治疗为了验证这一假设，提出了以下具体目标：1）确定 SAMHD 1在DNA DSB修复中的作用机制; 2）阐明SAMHD 1在DNA DSB修复中的作用机制， 在DNA DSB修复中受到调控; 3）确定SAMHD 1作为生物标志物的作用程度， 区分DNA损伤敏感性。这些目标将通过细胞生物学， 遗传学和生物化学方法。这些目标的完成将为SAMHD 1如何提供新的见解 通过促进HR维持基因组完整性并预防疾病，包括AGS、CLL和HIV 1感染。 此外，鉴于SAMHD 1调节细胞dNTP库和代谢DNA的独特能力， 也可以作为区分癌细胞对不同类型化疗药物的抗性的重要生物标志物。 诱导DNA损伤的癌症治疗，包括化疗和IR。 艾-古二氏症候群 慢性淋巴细胞白血病