Genes, genomes, and genotoxicity: in vivo epigenetic toxicology of 1,3-butadiene

描述（由申请人提供）：表观遗传eprogramming已被提出作为“基因组不稳定性”的组成部分，使癌细胞的特征。化学诱导 表观遗传变化可能是DNA损伤的结果，也可能是致癌的非遗传毒性机制的一部分。我们最近的研究提供了关键的额外的见解之间的联系遗传毒性和表观遗传致癌机制。首先，使用人类群体的多品系小鼠模型，我们表明重要的个体间（例如，菌株间）在经典遗传毒性致癌物1，3-丁二烯和其它化学品的遗传毒性和表观遗传毒性作用方面存在差异。其次，我们证实了染色质重塑反应是丁二烯诱导的DNA损伤中菌株间差异的潜在机制的假设。这些新的发现塑造了该项目的总体目标，即揭示基因组之间的机械联系（例如，DNA序列变体）、表观基因组（例如，染色质状态），和分子起始事件（例如，DNA损伤）引起的遗传毒性致癌物丁二烯在体内小鼠模型。两个特定目的将检验遗传变异性相关染色质重塑事件影响丁二烯遗传毒性潜力的假设。在特定目标1中，我们将扩展我们令人兴奋的发现，即近交系小鼠品系之间丁二烯诱导的DNA损伤程度的主要差异是表观遗传控制的染色质状态的结果。我们将利用基于深度测序的DNaseI超敏反应图谱和染色质免疫沉淀分析，对调节染色质状态的代表性组蛋白修饰进行分析，再加上RNA测序使能的基因表达分析和丁二烯特异性DNA损伤的测量。这些数据将允许更深入地了解毒物诱导的染色质的变化，在丁二烯敏感和耐药菌株。我们将在两种性别以及丁二烯诱导的致癌作用的靶组织和非靶组织中探索这些事件。在具体目标2中，使用类似的实验技术，我们将把染色质变异和丁二烯的遗传毒性效应与DNA序列变异联系起来。为此，我们将使用来自协作杂交资源的大量重组近交系小鼠，这是实验动物群体遗传学研究的独特而强大的工具。总之，该提案不仅将使用最新的工具来研究致癌物对基因组生物学的影响，而且还将为一个范式转变概念提供实验证据，即遗传决定的染色质状态调节遗传毒性暴露的疾病风险。

DESCRIPTION (provided by applicant): Epigenetic eprogramming has been proposed as an integral part of the "genome instability" enabling characteristic of cancer cells. Chemical-induced epigenetic changes may be a consequence of DNA damage, or may be part of the non-genotoxic mechanisms of carcinogenesis. Our recent studies provide critical additional insights into linkages between genotoxic and epigenetic mechanisms of carcinogenesis. First, using a multi-strain mouse model of the human population, we showed that important inter-individual (e.g., inter- strain) differences exist in both genotoxic and epigenotoxic effects of the classic genotoxic carcinogen 1, 3-butadiene and other chemicals. Second, we confirmed the hypothesis that the chromatin remodeling response is an underlying mechanism for the inter-strain differences in butadiene-induced DNA damage. These novel findings shaped this project's overall objective to uncover the mechanistic linkages between the genome (e.g., DNA sequence variants), epigenome (e.g., chromatin status), and molecular initiating events (e.g., DNA damage) elicited by a genotoxic carcinogen butadiene in an in vivo mouse model. Two Specific Aims will test the hypothesis that genetic variability-associated chromatin remodeling events affect the genotoxic potential of butadiene. In Specific Aim 1, we will extend our exciting finding that major differences in the extent of butadiene- induced DNA damage between inbred mouse strains are the result of epigenetically-controlled chromatin status. We will utilize deep sequencing-based DNaseI hypersensitivity mapping and chromatin immunoprecipitation analyses of representative histone modifications that regulate chromatin status, coupled with RNA sequencing-enabled gene expression analysis and measurements of butadiene-specific DNA damage. This data will permit deeper understanding of the toxicant-induced changes in chromatin in butadiene-sensitive and resistant strains. We will probe these events in both sexes and in target and non- target tissues for butadiene-induced carcinogenesis. In Specific Aim 2, using similar experimental techniques we will connect chromatin variation and genotoxic effects of butadiene with DNA sequence variation. To do so, we will use a large panel of recombinant inbred mouse lines from the Collaborative Cross resource, a unique and powerful tool for population genetics studies in experimental animals. In summary, this proposal not only will use the most novel tools to investigate carcinogen effects on genome biology, but it also will offer experimental proof to a paradigm-shifting concept that genetically-determined chromatin status modulates disease risk from genotoxic exposures.