Comparative Mechanisms of Genomic Instability

基因组不稳定性的比较机制

• 批准号: 7624605
• 负责人: Karen M Vasquez
• 金额: $ 35.84万
• 依托单位: UNIVERSITY OF TX MD ANDERSON CAN CTR
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-08-01 至 2011-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7624605
• 关键词: Adopted; Artificial Chromosomes; B-Cell Lymphomas; B-DNA; Benzo(a)pyrene; Burkitt Lymphoma; Candidate Disease Gene; Cells; Characteristics; Chromatin; Chromosomal Rearrangement; Chromosomal translocation; Chromosome Breakage; Chromosome Fragile Sites; Chromosomes; Classification; Complement; DNA; DNA Adduction; DNA Adducts; DNA Damage; DNA Double Strand Break; DNA Modification Process; DNA Sequence; DNA Structure; DNA lesion; DNA-Binding Proteins; Data; Development; Disease; Endogenous Factors; Environmental Carcinogens; Environmental Exposure; Environmental Pollution; Environmental Risk Factor; Enzymes; Epoxy Compounds; Excision; Exposure to; Frequencies; Genes; Genetic; Genetic Predisposition to Disease; Genetic Processes; Genetic Recombination; Genetic Risk; Genome; Genomic Instability; Genomics; Glycols; Goals; H-DNA; Human; Human Cell Line; Indium; Induced Mutation; Knock-out; Lead; Lesion; MYC gene; Malignant - descriptor; Malignant Neoplasms; Mammalian Cell; Measures; Mismatch Repair; Molecular Conformation; Mus; Mutagenesis; Mutation; Nucleotide Excision Repair; Oncogenic; Pathogenesis; Pathway interactions; Plasmids; Play; Point Mutation; Predisposition; Prevention; Process; Proteins; Radiation Genetics; Reporter; Reporter Genes; Research Personnel; Resistance; Risk Factors; Role; Sampling; Screening procedure; Series; Skin; Small Interfering RNA; Structure; Sunlight; System; Techniques; Testing; Transgenic Organisms; Translocation Breakpoint; Yeasts; Z-Form DNA; adduct; base; chromosome mutation; comparative; disorder control; disorder risk; environmental agent; high throughput screening; human disease; in vivo; internal control; irradiation; leukemia/lymphoma; mouse model; mutant; novel; novel strategies; overexpression; programs; repaired; research study; ultraviolet irradiation; vector

DESCRIPTION (provided by applicant): Chromosomal translocations resulting in inappropriate control of disease-related genes are important causative factors in environmentally induced disorders such as cancer. For example, translocations resulting in overexpression of the BCL-2 and c-MYC genes are the hallmarks of follicular B-cell lymphoma and Burkitt's lymphoma, respectively. DNA double-strand breaks (DSBs) are the first step in the process of chromosomal translocation. However, little is known about the mechanism(s) of the breakages on the translocated genes, why the DSBs tend to locate in certain genomic fragile site "hotspots", and the effects of environmental agents on the genomic instability at these susceptible hotspots. In this application, the intent is to use a comparative genetic approach to determine mechanisms of DNA structure-induced genomic instability. Interestingly, the most common breakpoints in such genes occur near regions that are capable of adopting non-B DNA structures. This group has discovered that H-DNA and Z-DNA-forming sequences near the translocation breakpoint hotspots in the human c-MYC gene induce DSBs, resulting in high levels of genetic instability in mammalian cells. Hence, the objectives of this application are to determine the mechanisms involved in genetic instabilities at breakpoint hotspots associated with disease, and further the development of novel approaches to reduce genetic instability caused by environmental DNA damaging agents. The immediate goals are to test the hypotheses that non-B-DNA structures found in the BCL-2 and c-MYC breakpoint regions are implicated in genetic instability across species, and that DNA damage induced by environmental factors at these hotspots enhance their susceptibility to genomic instability. The following are proposed: 1) to measure non-B DNA-induced genetic instability in different species. The naturally occurring H-DNA or Z-DNA-forming sequences from the human c-MYC and BCL-2 genes will be screened for their mutagenic potentials in a variety of species including yeast, mouse, and human. DNA structure-induced DSBs, illegitimate recombination, or point mutations in cells will be detected by facile blue/white screening; 2) to determine the susceptibility of non-B DNA-sequences to environmental carcinogen-induced DNA damage and mutagenesis. Environmental carcinogens such as irradiation are known to result in more non-B structure formation, and a reduced error-free repair of the damage. Thus, the amount of DNA damage induced and repaired in non-B sequences will be measured, and the level of genetic instability induced by environmental agents at these fragile site "hotspots" determined; and 3) to identify the genes/pathways that are involved in the genetic instability at non-B DNA sequences in the presence and absence of environmental carcinogens. Using a high-throughput screen gene products involved in DNA structure-induced genetic instability will be identified at genomic hotspots to begin to elucidate the pathways involved in genetic instability. Data obtained will give a better understanding of the mechanisms of genomic instability and the impact of environmental agents on these mechanisms. These discoveries should begin to unravel the pathogenesis of diseases that are caused by genomic instability, and ultimately to the development of new approaches for treatment and prevention.

描述（由申请人提供）： 染色体易位导致疾病相关基因的不适当控制是环境诱导的疾病如癌症的重要致病因素。例如，导致BCL-2和c-MYC基因过表达的易位分别是滤泡性B细胞淋巴瘤和伯基特淋巴瘤的标志。DNA双链断裂（DSB）是染色体易位过程的第一步。然而，对于易位基因的断裂机制、DSB为何倾向于定位于某些基因组脆性位点的“热点”以及环境因子对这些敏感热点基因组不稳定性的影响，目前还知之甚少。在本申请中，目的是使用比较遗传学方法来确定DNA结构诱导的基因组不稳定性的机制。有趣的是，这些基因中最常见的断裂点发生在能够采用非B DNA结构的区域附近。该小组发现，人类c-MYC基因中易位断裂点热点附近的H-DNA和Z-DNA形成序列诱导DSB，导致哺乳动物细胞中高水平的遗传不稳定性。因此，本申请的目的是确定与疾病相关的断点热点处的遗传不稳定性所涉及的机制，并进一步开发新的方法来减少由环境DNA损伤剂引起的遗传不稳定性。近期目标是检验以下假设，即BCL-2和c-MYC断裂点区域中发现的非B-DNA结构与跨物种的遗传不稳定性有关，并且由这些热点的环境因素诱导的DNA损伤增强了它们对基因组不稳定性的易感性。提出了以下建议：1）测量不同物种中非B DNA诱导的遗传不稳定性。将筛选来自人c-MYC和BCL-2基因的天然存在的H-DNA或Z-DNA形成序列在各种种属（包括酵母、小鼠和人）中的致突变潜力。DNA结构诱导的DSB、非法重组或细胞中的点突变将通过简单的蓝色/白色筛选进行检测; 2）确定非B DNA序列对环境致癌物诱导的DNA损伤和诱变的易感性。已知环境致癌物如辐射会导致更多的非B结构形成，并减少损伤的无错误修复。因此，将测量在非B序列中诱导和修复的DNA损伤的量，并确定由环境因子在这些脆弱位点“热点”处诱导的遗传不稳定性的水平;以及3）鉴定在存在和不存在环境致癌物的情况下在非B DNA序列处参与遗传不稳定性的基因/途径。使用高通量筛选，将在基因组热点处鉴定参与DNA结构诱导的遗传不稳定性的基因产物，从而开始阐明参与遗传不稳定性的途径。所获得的数据将更好地了解基因组不稳定性的机制和环境因素对这些机制的影响。这些发现应该开始揭开由基因组不稳定性引起的疾病的发病机制，并最终开发新的治疗和预防方法。