Function and Biology of Eukaryotic DNA Topoisomerases

真核 DNA 拓扑异构酶的功能和生物学

• 批准号: 8689073
• 负责人: NEIL OSHEROFF
• 金额: $ 34.48万
• 依托单位: VANDERBILT UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1984
• 资助国家: 美国
• 起止时间: 1984-07-01 至 2016-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8689073
• 关键词: 11q23; Acute Myelocytic Leukemia; Acute Promyelocytic Leukemia; Antineoplastic Agents; Bacillus anthracis; Bacterial Typing; Biology; Cancer Cell Growth; Catalytic DNA; Cell Death; Cell Survival; Cells; Chemicals; Chemotherapy-Oncologic Procedure; Chromosomal translocation; Chromosome Band; Chromosome Segregation; Chromosome Structures; Cleaved cell; Complex; Curcumin; DNA; DNA Damage; DNA Double Strand Break; DNA Topoisomerase IV; DNA Topoisomerases; DNA biosynthesis; DNA strand break; Development; Diet; Disease; Drug Prescriptions; Drug Targeting; Enzymes; Epirubicin; Etoposide; Fluorouracil; Generations; Genetic Materials; Genetic Recombination; Genetic Transcription; Genomics; Geometry; Goals; Handedness; Human; Infant; Intercalating Agents; Isomerase; Lead; MLL gene; Malignant Neoplasms; Maternal Exposure; Mediating; Mitoxantrone; Neurofibrillary Tangles; Oxidation-Reduction; PML gene; Pathway interactions; Patients; Pharmaceutical Preparations; Physiological; Play; Poison; Pregnancy; Proliferating; Protein Isoforms; Proteins; Quinolones; Reaction; Research; Risk; Role; Study models; Superhelical DNA; Techniques; Time; Topoisomerase; Topoisomerase II; Toxin; cell killing; clinically relevant; design; innovation; leukemia; novel; research study; response; segregation; single molecule

DESCRIPTION (provided by applicant): Type II topoisomerases are ubiquitous enzymes that are required for proper chromosome structure and segregation and play important roles in DNA replication, transcription, and recombination. Type II topoisomerases relax DNA and remove knots and tangles from the genetic material by passing an intact double helix (transport segment) through a transient double-stranded break that they generate in a separate DNA segment (gate segment). Humans encode two closely related isoforms of the type II enzyme, topoisomerase II¿ and topoisomerase II¿. Topoisomerase II¿ is essential for the survival of proliferating cells and topoisomerase II¿ plays critical roles during development. However, because these enzymes generate requisite double-stranded DNA breaks during their crucial catalytic functions, they assume a dual persona. Although essential to cell survival, they also pose an intrinsic threat to genomic integrity every time they act. Beyond their critical physiological functions, topoisomerase II¿ and II¿ are the primary targets for some of the most active and widely prescribed drugs currently used for the treatment of human cancers. These agents kill cells by increasing levels of covalent topoisomerase II-cleaved DNA complexes that are normal, but fleeting, intermediates in the catalytic DNA strand passage reaction. Most clinically relevant drugs do so by inhibiting the ability of the type II enzymes to ligate cleaved DNAs. When the resulting enzyme-associated DNA breaks are present in sufficient concentrations, they can trigger cell death pathways. Anticancer drugs that target type II enzymes are referred to as topoisomerase II poisons because they convert these indispensable enzymes to potent physiological toxins that generate DNA damage in treated cells. Although topoisomerase II¿ and II¿ are important targets for cancer chemotherapy, evidence suggests that they also have the potential to trigger specific leukemias. A small percentage of cancer (and other) patients treated with topoisomerase II-targeted drugs eventually develop acute myeloid leukemias (AMLs) involving the MLL gene at chromosome band 11q23 or acute promyelocytic leukemias involving 15:17 translocations. The 11q23 chromosomal translocations also are seen in infant AMLs, and the risk of these leukemias rises ~3-fold when there is high maternal exposure during pregnancy to environmental and dietary topoisomerase II poisons. Despite the importance of the type II enzymes to cell growth and cancer, interactions between human topo- isomerase II and DNA, anticancer drugs, and other topoisomerase II poisons have not been well characterized. Thus, the aims of this proposal are to further define the catalytic mechanism of topoisomerase II, to further delineate the mechanism by which topoisomerase poisons increase levels of enzyme-mediated DNA breaks, and to determine the cellular consequences of topoisomerase II poisons. The primary research model for this study will be human topoisomerase II¿ and II¿. Bacillus anthracis gyrase and topoisomerase IV will be used for some experiments to provide comparisons between the prokaryotic and eukaryotic type II enzymes.

描述（由申请人提供）： II型拓扑异构酶是无处不在的酶，对于适当的染色体结构和隔离所需，在DNA复制，转录和重组中起重要作用。 II型拓扑异构酶松弛DNA，并通过将完整的双螺旋（传输段）通过瞬态双链断裂，从遗传材料中取出结和缠结，它们在单独的DNA段（栅极段）中产生。人类编码了II型酶，拓扑异构酶II和拓扑异构酶II型的两个密切相关的同工型。拓扑异构酶II ??对于增殖细胞和拓扑异构体的生存至关重要，在发育过程中起着至关重要的作用。但是，由于这些酶在关键的催化功能期间会产生必要的双链DNA断裂，因此它们假定双重角色。尽管对细胞存活至关重要，但它们每次作用时也会对基因组完整性构成内在威胁。除了其关键的生理功能外，拓扑异构酶II¿和II？这些药物通过增加正常但短暂的催化性DNA链传递反应中的中间体而增加的共价拓扑异构酶II裂解的DNA复合物来杀死细胞。大多数临床相关的药物通过抑制II型酶结扎裂解DNA的能力来做到这一点。当产生的酶相关的DNA断裂以足够的浓度存在时，它们会触发细胞死亡途径。靶向II型酶的抗癌药被称为拓扑异构酶II毒物，因为它们将这些必不可少的酶转化为潜在的生理毒素，这些毒素会在处理过的细胞中产生DNA损伤。尽管拓扑异构酶II¿和ii？是癌症化学疗法的重要靶标，但有证据表明它们也有触发特定白血病的潜力。用拓扑异构酶II靶向药物治疗的一小部分癌症（和其他）患者最终会产生涉及染色体带11q23的MLL基因的急性髓样白血病（AMLS）或涉及15:17易位的急性临床前的白血病。 11q23染色体易位也是婴儿的AML，当怀孕期间出现高产母暴露于环境和饮食拓扑异构酶II毒药时，这些白血病的风险会增加3倍。尽管II型酶对细胞生长和癌症的重要性很重要，但人类顶级异构酶II与DNA，抗癌药物和其他拓扑异构酶II毒药之间的相互作用尚未得到很好的特征。这是该提案的目的是进一步定义拓扑异构酶II的催化机制，以进一步描述拓扑异构酶毒药增加酶介导的DNA断裂水平的机制，并确定拓扑异构酶II毒药的细胞后果。这项研究的主要研究模型将是人类拓扑异构酶II¿和II。炭疽芽孢杆菌和拓扑异构酶IV将用于某些实验，以提供原核和真核II型酶之间的比较。