Effect of the Spiroiminodihydantoin Lesion on DNA Helix Stability and Nucleosome

描述（由申请人提供）：脱氧核糖核酸（DNA）是细胞内负责传递和存储遗传信息的生物分子。不幸的是，DNA可能会被破坏，危及这些对保持健康至关重要的信息的完整性。破坏DNA的物质，被称为活性氧（ROS），是在细胞呼吸的正常过程中产生的，因为细胞通过将氧气转化为水来产生能量。它们也可以由外部来源引入，如电离辐射和某些过渡金属。这里提出的实验将集中于检查一种称为DNA碱基氧化的特定类型的DNA损伤，在这种损伤中，负责存储遗传信息的DNA碱基的结构被改变。这种特殊类型的DNA损伤与细胞衰老、癌症以及阿尔茨海默病和肌萎缩侧索硬化症等神经系统疾病有关。本研究的目的是研究螺酰亚胺二氢妥英（Sp）损伤对DNA稳定性和结构的影响。当活性氧与DNA中的鸟嘌呤碱基发生反应时，这种高度诱变的病变会产生与某些人类肺肿瘤相同类型的突变。差示扫描量热法（DSC）实验将在具体目标1和2中进行，以充分检查各种DNA序列中Sp病变的两种不同异构体形式的热力学稳定性。Sp病变在核小体中的形成和包装将在Specific Aim 3中进行检查，以研究这种病变对真核细胞的影响。这些研究的结果将为了解细胞中Sp病变的生物学过程如何导致癌症等疾病提供重要的见解。

DESCRIPTION (provided by applicant): Deoxyribonucleic acid (DNA) is the biological molecule within cells that is responsible for transmitting and storing genetic information. Unfortunately, DNA can become damaged, jeopardizing the integrity of this information that is vital for preserving health. Agents that damage DNA, known as reactive oxygen species (ROS), are produced in the normal course of cellular respiration as cells make energy by converting oxygen into water. They can also be introduced by outside sources such as ionizing radiation and certain transition metals. The experiments proposed here will focus on examining a specific type of DNA damage called DNA base oxidation, where the structure of the DNA base, responsible for storing genetic information, is altered. This particular type of DNA damage has been implicated in causing cellular aging, cancer, and neurological disorders like Alzheimer's disease and amyotrophic lateral sclerosis. The goal of this proposal is to investigate the effect of the spiroiminodihydantoin (Sp) lesion on the stability and structure of DNA. This highly-mutagenic lesion, which is formed when ROS react with guanine bases in DNA, produces the same types of mutations found in some human lung tumors. Differential scanning calorimetry (DSC) experiments will be undertaken in Specific Aims 1 & 2 to fully examine the thermodynamic stability of the two different isomeric forms of the Sp lesion in a variety of DNA sequences. The formation and packaging of Sp lesions in nucleosomes will be examined in Specific Aim 3 to investigate the impact of this lesion on eukaryotic cells. The results from these studies will provide important insight into how the biological processing of the Sp lesion in cells contributes to causing diseases like cancer. PUBLIC HEALTH RELEVANCE: Oxidative DNA damage can cause cellular aging, cancer, and neurological disorders. The goal of this proposal is to investigate the effect of a particular type of this damage, known as the spiroiminodihydantoin (Sp) lesion, on the stability and structure of DNA. The results from these studies will provide important insight into how the biological processing of the Sp lesion contributes to causing disease.