Mutational spectra of bulky DNA lesions

许多环境毒素破坏DNA并导致疾病。细胞暴露在DNA损伤剂中 导致一系列不同的DNA损伤的形成，其中的一部分可能会导致突变。如果有 如果要绘制突变的频率和类型作为基因位置的函数，则分布是 产生的突变谱通常被称为突变谱。突变谱通常发生在 突变事件发生频率比预期更高的地点。这些都是突变热点， 热点的形成可能有三种情况：形成、修复和复制。这是合理的 推测这些事件受到碱基周围的局部序列环境的调制 被修改，或DNA损伤需要修复或复制。对环境科学家来说，提供 对在显性临床症状之前预示肿瘤发展的进化变化的洞察 出现。这一目标是至关重要的，因为一些疾病，如肿瘤，在 疾病已经到了晚期，通常是致命的阶段。早期发病的基因组生物标志物可能使干预成为可能 消除或抑制疾病的发展。由特定毒素引起的疾病的生物标志物可以是 通过研究毒素产生的DNA损伤的突变光谱获得。一种新型材料的实验研究 由环境毒素引起的突变和突变谱传统上集中在单个 突变。然而，突变热点的起源受到邻近环境的影响而变得复杂。精挑细选 原则上，dna损伤的形成、复制和修复可以受到周围核苷酸的影响。 环境从5‘端和3’端开始。某一DNA损伤的最近邻分析(NXN，X=损伤，N (四种核苷酸中的一种)将为环境毒素的突变谱提供结构基础 相关的人类肿瘤。在这项建议中，我们将研究所有环境毒素的个别损害。 遗传和表观遗传的相关背景。在本项目中，我们选择了两种重要的环境毒素，4-氨基 联苯(ABP)和氨基甲卡林(AAC)研究其主要DNA损伤的突变谱和 与由它们引起的疾病的突变特征相关。这个项目的中心假设是 环境毒素产生的DNA损伤会导致不同的序列依赖的突变谱 举止。具体目标为：特定目标1：块状DNA加合物的化学合成与鉴定 含有寡核苷酸的。特定目标2：细胞内块状病变的突变谱。具体目标3： 通过跨病变合成聚合酶对病变进行复制旁路。在这个项目结束时，我们将 已经证明了环境毒素和突变光谱之间的相互作用。这些研究 应综合运用遗传、化学和光谱手段来理解和操纵 分子水平上的生物系统。

Many environmental toxins damage DNA and cause diseases. The exposure of cells with DNA damaging agents results in the formation of a host of different DNA lesions, a subset of which can give rise to mutations. If one were to plot the frequency and type of mutation as a function of the position along a gene, a distribution is generated that is commonly referred to as a mutational spectrum. Mutational spectra are usually happened by sites at which mutagenic events occur more frequently than expected. These are mutational hotspots and the formation of hotspots can arise from three scenarios: formation, repair and replication. It is reasonable to speculate that these events are modulated by the local sequence environment surrounding the base to be modified, or the DNA lesion to be repaired or replicated. It is important for environmental scientists to provide insights into the evolutionary changes that foreshadow tumor development before overt clinical symptoms appear. This goal is crucial because some diseases, such as tumors, show few clinical symptoms until the disease has reached a late, usually fatal stage. Early onset genomic biomarkers might enable intervention to eliminate or curtail development of the disease. The biomarkers of a disease caused by a specific toxin can be obtained by studying the mutational spectra of DNA lesions generated from the toxin. Experimental studies of the mutations and mutation spectra induced by environmental toxins have traditionally focused on single mutations. However, the origins of mutational hotspots is complicated by the neighboring contexts. The selective formation, replication, and repair of a DNA lesion can, in principle, be influenced by the surrounding nucleotide environment from both 5’ and 3’ ends. A nearest-neighbor analysis of a certain DNA lesion (NXN, X = lesion, N = one of the four nucleotides) will provide a structural rationale for mutational spectra in environmental toxin related human tumors. In this proposal, we will study individual lesions of environmental toxins under all the genetic and epigenetic relevant contexts. In this project, we select two important environmental toxins, 4-amino biphenyl (ABP) and amino alpha carboline (AaC) to study the mutational spectra of their major DNA lesions and correlate with mutational signatures of diseases caused by them. The central hypothesis of this project is that DNA lesions generated by environmental toxins will cause different mutational spectra in a sequence dependent manner. The Specific Aims are: Specific Aim 1: Chemical synthesis and identification of bulky DNA adduct containing oligonucleotides. Specific Aim 2: Mutational spectra of bulky lesions in cell. Specific Aim 3: Replication bypass of lesions by translesion synthesis polymerases. At the conclusion of this project we will have demonstrated how the interaction between environmental toxins and mutational spectra. These studies shall utilize in a combination of genetic, chemical, and spectroscopic tools to understand and manipulate biological systems at the molecular level.