Mechanisms of Obesity-Induced Genetic Instability at Endogenous Mutation Hotspots

项目总结 这项建议的总体目标是了解饮食能量平衡，特别是肥胖 在内源突变“热点”影响基因组稳定性。为了实现这一目标，我们将使用小说 我们开发的用于确定肥胖对DNA结构诱导的影响的小鼠模型 在这些小鼠的不同组织中进行突变。重复的DNA序列广泛分布于 哺乳动物基因组，可以采用替代的(非B-DNA)二级结构，如H-DNA和Z-DNA DNA重要的是，这些非B DNA结构形成序列在内源显著富含 人类癌症基因组中的突变热点，表明它们与癌症病因学有关。例如，H-DNA- 在Burkitt淋巴瘤易位断裂热点发现c-myc基因的形成序列 急性B细胞淋巴瘤。我们已经开发出含有人H-DNA和Z-DNA的新型突变报告小鼠 与易位断点热点共定位的DNA形成序列，并首次展示 这些序列在体内发生突变的时间。众所周知，肥胖会增加细胞的氧化应激，并 氧化DNA损伤，而卡路里限制已被证明可以减少细胞氧化应激， 氧化DNA损伤，减少突变，增强DNA修复途径。此外，肥胖是一种 这是许多癌症的重要风险因素。然而，饮食能量平衡的程度 尤其是肥胖影响DNA结构，导致的遗传不稳定性尚不清楚。因此，美国的一个目标是 拟议的工作就是填补这一知识空白。在这个提案中，我们将检验肥胖症的工作假设 增加DNA结构引起的遗传不稳定性。我们将研究饮食引起的肥胖的影响和 热量限制对dna结构诱变小鼠的影响。将对几种不同的组织进行评估 以确定是否存在任何组织特异性差异，以响应 能量平衡操纵。我们还将探索肥胖对DNA结构的影响机制- 导致遗传不稳定。我们将重点研究肥胖对DNA修复机制的影响，如 最近的几项研究表明，肥胖损害了多条DNA修复途径，包括非 同源末端连接，我们已经发现在非B DNA的加工过程中发挥作用的修复途径。在……里面 此外，我们还发现FEN1(FEN1)在无错加工中起着重要作用 Non-B DNA和它的水平受饮食能量平衡的调节。这些观察也将是 在这项提案中进行了更详细的探讨。完成拟议的研究将带来更大的 了解肥胖如何影响癌症病因学。此外，这项工作将导致识别 预防和/或治疗肥胖相关癌症的新目标。

PROJECT SUMMARY The overall objective of this proposal is to understand how dietary energy balance and especially obesity influences genome stability at endogenous mutation “hotspots”. To achieve this objective, we will use novel mouse models that we have developed to determine the impact of obesity on DNA structure-induced mutagenesis in various tissues from these mice. Repetitive DNA sequences are widely dispersed throughout mammalian genomes and can adopt alternative (non-B DNA) secondary structures, such as H-DNA and Z- DNA. Importantly, these non-B DNA structure-forming sequences are significantly enriched at endogenous mutation hotspots in human cancer genomes, implicating them in cancer etiology. For example, H-DNA- forming sequences in the c-MYC gene are found at translocation breakage hotspots in Burkitt’s lymphoma and acute B-cell lymphoma. We have developed novel mutation-reporter mice containing human H-DNA- and Z- DNA-forming sequences that co-localize with translocation breakpoint hotspots, and demonstrated for the first time that these sequences are mutagenic in vivo. Obesity is known to increase cellular oxidative stress and oxidative DNA damage, whereas calorie restriction has been shown to decrease cellular oxidative stress, oxidative DNA damage, reduce mutagenesis and to enhance DNA repair pathways. In addition, obesity is an important risk factor for a significant number of cancers. However, the extent to which dietary energy balance and especially obesity influences DNA structure-induced genetic instability is not known. Thus, a goal of the proposed work is to fill this gap in knowledge. In this proposal, we will test the working hypothesis that obesity increases DNA structure-induced genetic instability. We will examine the impact of diet-induced obesity and calorie restriction on DNA structure-induced mutagenesis in mice. Several different tissues will be evaluated from these mice to determine whether there are any tissue specific differences in mutagenesis in response to energy balance manipulation. We will also explore mechanisms for the impact of obesity on DNA structure- induced genetic instability. We will focus our studies on the impact of obesity on DNA repair mechanisms as several recent studies have suggested that obesity impairs multiple DNA repair pathways, including non- homologous end-joining, a repair pathway that we have found to play a role in the processing of non-B DNA. In addition, we have found that flap endonuclease 1 (FEN1) plays an important role in error-free processing of non-B DNA and that its levels are modulated by dietary energy balance. These observations will also be explored in more detail in this proposal. Completion of the proposed studies will lead to a greater understanding of how obesity influences cancer etiology. In addition, this work will lead to the identification of novel targets for the prevention and/or treatment of obesity-related cancers.