Repair of Genome Destabilizing DNA Structures

DNA损伤和修复是人类健康和疾病的基础。这个项目的长期目标是 应用：扩大我们对DNA螺旋扭曲在DNA损伤中的作用的理解 识别和处理；确定影响DNA结构引起的遗传不稳定性的因素； 阐明与某些癌症相关的易位的潜在机制；以及进一步 开发减少人类细胞遗传不稳定性的新方法。在短期内，我们将 继续我们最近的发现，由自然产生的Z-DNA和H-DNA引起的螺旋扭曲 结构是高度诱变的，可以在哺乳动物细胞中诱导DNA双链断裂(DSB)。我们 建议研究DNA螺旋扭曲对以质粒为基础的系统中基因组不稳定性的影响 在人类细胞和转基因突变报告鼠的染色体上也是如此。我们将重点关注H- 位于人c-myc启动子易位断裂点附近的DNA形成序列和Z- 位于人类bcl2基因染色体断裂点的DNA序列，发现于淋巴瘤和 白血病。我们将确定(S)DNA修复、复制和转录在结构诱导中的作用 遗传不稳定。我们将利用我们的专业知识将特定部位的DNA螺旋扭曲引入 明确定义的分子间三链结构的形式来检验我们的假设，即某些类型的DNA是螺旋的 DNA修复机制可以识别DNA损伤本身的扭曲(存在或不存在 在人类细胞中。从这些研究中获得的新信息将为深入了解 非B型DNA引起的遗传不稳定；人类DNA修复中的限速步骤(即扭曲/损伤 识别)；以及在处理DNA过程中核苷酸切除修复和错配修复之间的重叠 螺旋扭曲。它还将确定参与由非金属离子诱导的DSB产生的蛋白质。 典型的DNA结构在映射到人类癌症易位断裂点的序列上形成。 这些发现应该有助于更好地理解癌症和其他疾病的发病机制。 是由DNA损伤和自然发生的螺旋扭曲引起的，最终导致 开发新的治疗和预防方法。

DNA damage and repair are fundamental to human health and disease. The long-term objectives of this application are to: expand our understanding of the role of DNA helical distortions in DNA damage recognition and processing; determine the factors influencing DNA structure-induced genetic instability; elucidate potential mechanisms involved in translocations associated with certain cancers; and further the development of novel approaches to reduce genetic instability in human cells. In the short term, we will pursue our recent discovery that helical distortions induced by naturally occurring Z-DNA and H-DNA structures are highly mutagenic and can induce DNA double-strand breaks (DSBs) in mammalian cells. We propose to study the effect of DNA helical distortions on genomic instability in plasmid-based systems as well as on chromosomes in human cells and in transgenic mutation-reporter mice. We will focus on the H- DNA-forming sequence located near the translocation breakpoint in the human c-MYC promoter and the Z- DNA sequence located at a chromosomal breakpoint in the human BCL-2 gene, found in lymphomas and leukemias. We will determine the role(s) of DNA repair, replication and transcription in the structure-induced genetic instability. We will use our expertise in the introduction of site-specific DNA helical distortions in the form of well-defined intermolecular triplex structures to test our hypothesis that certain types of DNA helical distortions (in the presence or absence of DNA damage per se) are recognized by the DNA repair machinery in human cells. The new information obtained from these studies will provide insight into the mechanisms of non-B DNA-induced genetic instability; the rate-limiting step in human DNA repair (i.e.distortion/damage recognition); and the overlap between nucleotide excision repair and mismatch repair in processing DNA helical distortions. It will also identify the proteins involved in the generation of DSBs induced bynon- canonical DNA structures formed at sequences that map to translocation breakpoints in human cancers. These discoveries should lead to a better understanding of the pathogenesis of cancers and other diseases that are caused by DNA damage and naturally occurring helical distortions, and ultimately to the development of new approaches to treatment and prevention.