Repair of Genome Destabilizing DNA Structures

项目摘要 衰老和癌症是密不可分的。基因组不稳定性是衰老和癌症的共同点， 遗传不稳定性和癌症风险随着年龄的增长而增加。然而，在理解这一点上存在着根本性的差距。 随着年龄的增长，基因不稳定性会增加。因此，本报告的总体目标 应用就是要填补这一知识空白。突变不是随机的，存在内源性突变 基因组的“热点”区域。重要的是，许多这些癌症相关的突变热点共定位于 具有并富集了能够采用替代结构的DNA（即非B DNA）的序列， 这表明这些序列与癌症病因有关。我们已经发现天然存在的非B DNA;例如， Z-DNA和H-DNA在哺乳动物中具有致突变性，并且这种DNA结构诱导的突变随着年龄的增长而增加。 然而，在这些热点地区，与年龄相关的遗传不稳定性传播的机制是 不清楚因此，目标是确定DNA结构诱导的遗传不稳定性所涉及的机制， 以及年龄增长对这些内源性突变热点产生的影响。我们还 发现非B DNA由DNA修复和复制蛋白处理。这些发现为 对于未来的科学前提，以测试癌症相关DNA结构诱导的新假设， 遗传不稳定性随着年龄的增长而增加，因为随着年龄的增长，非B DNA（即内源性突变热点） 变得越来越难修复;此外，非B DNA容易出错， 随着年龄增长。这两种机制都导致了年龄依赖性突变的产生。远景目标 阐明衰老对突变热点处遗传不稳定性的影响，以确定 年龄相关的和组织特异性DNA结构诱导的癌症病因学遗传不稳定性， 降低遗传不稳定性以预防和/或治疗年龄相关疾病的新方法。这些目标是 确定年龄在小鼠特定组织中DNA结构诱导的基因组不稳定性中的作用， 确定复制依赖和非依赖遗传不稳定性的机制。我们将使用小说 突变报告小鼠，我们已经开发，以确定年龄对致突变潜力的影响， 非B DNA序列，并确定这些诱变序列的加工机制。这 是创新的，因为它将测试新的假设，即DNA结构诱导的遗传不稳定性增加 这些结构形成序列是由DNA修复机制处理的 其效率随着年龄的增长而下降。预期的贡献是阐明年龄对遗传的影响， 不稳定性和参与癌症中内切酶突变热点产生的机制， 更好地了解年龄相关疾病的病因。这是重要的，因为结果将有助于 制定新的战略，以减轻与年龄有关的疾病。

PROJECT SUMMARY Aging and cancer are inextricably linked. Genome instability is common to both aging and cancer, whereby genetic instability and cancer risk increase with age. However, there is a fundamental gap in understanding the mechanisms that predispose us to increased genetic instability as we age. Thus, the overall objective of this application is to fill this gap in knowledge. Mutations are not random, and there are endogenous mutation “hotspot” regions of the genome. Importantly, many of these cancer-assoicated mutation hotspots co-localize with, and are enriched at sequences capable of adopting alternatively structured DNA (i.e. non-B DNA), implicating these sequences in cancer etiology. We have discovered that naturally occurring non-B DNA; e.g., Z-DNA and H-DNA, is mutagenic in mammals, and this DNA structure-induced mutation increases with age. However, the mechanisms involved in the age-related propagation of genetic instability at these hotspots are unclear. Thus, a goal is to determine the mechanisms involved in DNA structure-induced genetic instability, and the impact of increased age on the generation of these endogenous mutation hotspots. We have also found that non-B DNA is processed by DNA repair and replication proteins. These findings provide the basis for the scientific premise going forward to test the novel hypothesis that cancer relevant DNA structure-induced genetic instability increases with age, because with age, non-B DNA (i.e. an endogenous mutation hotspot) becomes increasingly refractory to repair; moreover, non-B DNA is subject to error-prone processing that increases with age. Both mechanisms lead to the generation of age-dependent mutations. The long-term goals are to elucidate the impact of aging on genetic instability at mutation hotspots, to determine the mechanisms of age-related, and tissue-specific DNA structure-induced genetic instability in cancer etiology, and to develop novel approaches to reduce genetic instability to prevent and/or treat age-related disease. The objectives are to determine the role(s) of age in DNA structure-induced genomic instability in specific tissues of mice, and to identify the mechanisms of replication-dependent and -independent genetic instability. We will use novel mutation-reporter mice that we have developed to determine the effects of age on the mutagenic potential of non-B DNA sequences, and determine the mechanisms of the processing of these mutagenic sequences. This is innovative because it will test the novel hypothesis that DNA structure-induced genetic instability increases with age in mammals, and that these structure-forming sequences are processed by DNA repair mechanisms whose efficiency decline with age. The expected contribution is the elucidation of the impact of age on genetic instability and of the mechanisms involved in the generation of endogeous mutation hotspots in cancer, to provide a better understanding of age-related disease etiology. This is significant because the results will aid in the development of new strategies to mitigate age-related diseases.