Function and Biology of Eukaryotic DNA Topoisomerases

真核 DNA 拓扑异构酶的功能和生物学

基本信息

批准号：
8387856
负责人：
NEIL OSHEROFF
金额：
$ 34.48万
依托单位：
VANDERBILT UNIVERSITY
依托单位国家：
美国
项目类别：
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/8387856
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 Delivery Systems Drug Prescriptions Enzymes Epirubicin Etoposide Fluorouracil Generations Genetic Materials Genetic Recombination Genetic Transcription Genomics 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

项目摘要

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. PUBLIC HEALTH RELEVANCE: Type II topoisomerases are ubiquitous enzymes that remove knots and tangles from the genetic material by passing an intact double helix through a transient double-stranded break that they generate in a separate DNA segment. These enzymes are targets for important anticancer drugs, but are also are capable of triggering specific types of leukemias. In order to more fully understand these essential enzymes and develop safer topoisomerase II-targeted anticancer drugs, we propose to further determine how type II enzymes function, how drugs and other chemicals alter their activities, and how cells respond to topoisomerase II-targeted agents.

描述（由申请人提供）： II 型拓扑异构酶是适当染色体结构和分离所需的普遍存在的酶，在 DNA 复制、转录和重组中发挥着重要作用。 II 型拓扑异构酶通过完整的双螺旋（运输）松弛 DNA 并消除遗传物质中的结和缠结。人类编码两种密切相关的 II 型酶拓扑异构酶亚型。 II¿和拓扑异构酶 II¿拓扑异构酶 II¿对于增殖细胞和拓扑异构酶 II 的生存至关重要？然而，由于这些酶在其关键的催化功能中产生必要的双链 DNA 断裂，因此它们具有双重角色，尽管它们对细胞生存至关重要，但它们每次发挥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之外，拓扑异构酶 II¿和 II¿是目前用于治疗人类癌症的一些最活跃且广泛使用的药物的主要靶标，这些药物通过增加共价拓扑异构酶 II 切割的 DNA 复合物的水平来杀死细胞，这些 DNA 复合物是催化 DNA 中正常但短暂的中间体。大多数临床相关药物通过抑制 II 型酶连接切割 DNA 的能力来实现这一点，当产生的酶相关 DNA 断裂达到足够浓度时，它们可以引发细胞死亡。针对 II 型酶的抗癌药物被称为拓扑异构酶 II 毒物，因为它们将这些必不可少的酶转化为有效的生理毒素，从而在治疗的细胞中产生 DNA 损伤。和 II¿是癌症化疗的重要靶标，有证据表明它们也有可能引发特定的白血病。接受拓扑异构酶 II 靶向药物治疗的一小部分癌症（和其他）患者最终会发展为涉及 MLL 基因的急性髓系白血病 (AML)。染色体带 11q23 或涉及 15:17 易位的急性早幼粒细胞白血病 11q23 染色体易位也见于婴儿。当母亲在怀孕期间大量接触环境和膳食拓扑异构酶 II 毒物时，AML 和这些白血病的风险会增加约 3 倍。尽管 II 型酶对细胞生长和癌症很重要，但人类拓扑异构酶 II 和 DNA 之间的相互作用。、抗癌药物和其他拓扑异构酶II毒物尚未得到很好的表征，因此，本提案的目的是进一步明确拓扑异构酶II的催化机制，以进一步确定拓扑异构酶II的催化机制。描述拓扑异构酶毒物增加酶介导的 DNA 断裂水平的机制，并确定拓扑异构酶 II 毒物的细胞后果。本研究的主要研究模型将是人类拓扑异构酶 II。和 II¿炭疽芽孢杆菌旋转酶和拓扑异构酶 IV 将用于一些实验，以提供原核和真核 II 型酶之间的比较。公共卫生相关性： II 型拓扑异构酶是一种普遍存在的酶，可通过在单独的 DNA 片段中产生的短暂双链断裂传递完整的双螺旋，从而消除遗传物质中的结和缠结。这些酶是重要的抗癌药物的靶点。为了更全面地了解这些必需酶并开发更安全的靶向II型拓扑异构酶的抗癌药物，我们进一步确定II型酶如何能够引发特定类型的白血病。功能、药物和其他化学物质如何改变其活性，以及细胞如何响应拓扑异构酶 II 靶向药物。