Bisphenol A modulation of DNA repair triggered by environmental genotoxic stress

描述（由候选人提供）：双酚A（BPA）在食品和饮料容器中非常普遍，人类暴露无处不在。目前的BPA研究已经评估了BPA单独的遗传毒性，但没有研究其在不断受到各种环境DNA损伤剂的人体组织中损伤DNA的潜力，例如，食品添加剂溴酸钾，或紫外线辐射。为了解决这一关键差距，拟议的研究将检查BPA与饮食和环境DNA损伤剂的共同暴露。初步结果表明，BPA与外源氧化剂的共同暴露可增强细胞存活并抑制氧化DNA损伤的去除。拟议的研究将调查BPA和环境DNA损伤剂的共同暴露改变DNA修复能力并诱导BPA遗传毒性效应的假设。在指导K99阶段，我将描述BPA对通过碱基切除修复去除氧化DNA损伤的影响。在Samuel H. Wilson，DNA修复领域的领导者，我将研究BPA利用OGG 1 DNA糖基化酶抑制DNA损伤识别和/或切除的机制，OGG 1 DNA糖基化酶负责消除氧化损伤病变，8-oxoG。研究将利用体内和体外测定来定量DNA链断裂，确定8-oxoG病变的持续性，并确定OGG 1活性下调的机制。这将建立BPA改变DNA修复的工作假设，并为我继续作为独立研究者提供必要的培训。在R 00阶段，我将通过检查BPA抑制碱基切除修复的特异性来扩展K99阶段的研究。BPA与其他DNA损伤剂（如UV辐射）的共暴露将被表征，以确定BPA是否特异性抑制8-oxoG相对于其他病变的去除。在此阶段，我还将研究BPA诱导的BER抑制是否会导致基因组不稳定。我将确定损伤持续性是否导致突变增加，并将检查染色体重排以确定损伤去除是否通过刺激同源重组完成。K99提案将提供必要的指导和关键研究技术，以表征BPA单独和BPA与破坏剂组合对BER的影响。该项目的这一阶段将为我提供必要的技能基础，以过渡到一个独立的环境健康调查研究大学。作为一名独立的研究者，我将继续研究BPA、其他遗传毒性物质和DNA修复缺陷调节DNA修复能力的能力，并将描述这些影响对人类疾病和疾病进展的后果。这些短期和长期研究将通过以下方式实现NIEHS的战略目标：1）了解BPA的综合效应，2）将BPA的遗传毒性与人类健康影响联系起来，3）确定暴露反应的分子机制，4）培训下一代环境科学家。

DESCRIPTION (provided by candidate): Bisphenol A (BPA) is highly prevalent in food and beverage containers, and human exposure is ubiquitous. Current BPA research has assessed the genotoxicity of BPA alone but does not examine its potential to damage DNA in human tissues constantly subjected to a variety of environmental DNA damaging agents, e.g., the food additive potassium bromate, or UV-radiation. To address this critical gap, the proposed study will examine co-exposure of BPA with dietary and environmental DNA damaging agents. Preliminary results indicate that co-exposure of BPA with exogenous oxidants enhances cell survival and suppresses removal of oxidative DNA lesions. The studies proposed will investigate the hypothesis that co-exposure of BPA and environmental DNA damaging agents alters DNA repair capacity and induces BPA genotoxic effects. During the mentored K99 phase, I will characterize the effect of BPA on the removal of oxidative DNA damage by base excision repair. Under the mentorship of Dr. Samuel H. Wilson, a leader in the DNA repair field, I will investigate the mechanism that BPA utilizes to suppress DNA damage recognition and/or excision by the OGG1 DNA glycosylase, responsible for removing the oxidative damage lesion, 8-oxoG. Studies will utilize in vivo and in vitro assays to quantify DNA strand breaks, determine the persistence of 8-oxoG lesions, and identify mechanisms of down-regulation of OGG1 activity. This will establish the working hypothesis that BPA alters DNA repair, and provide the essential training for me to continue as an independent investigator. In the R00 phase, I will extend the studies of the K99 period by examining the specificity of BPA for suppressing base excision repair. Co-exposure of BPA with other DNA damaging agents, like UV-radiation, will be characterized to determine if BPA specifically suppresses removal of 8-oxoG vs. other lesions. During this phase, I will also investigate whether BPA-induced suppression of BER results in genomic instability. I will determine if lesion persistence results in increased mutagenesis and chromosomal rearrangements will be examined to determine if lesion removal is accomplished by stimulation of homologous recombination. The K99 proposal will provide the mentoring and critical research techniques necessary to characterize the effects of BPA alone and BPA in combination with damaging agents on BER. This phase of the project will provide me with the foundation of skills necessary to transition into an independent environmental health investigator at a research university. As an independent investigator, I will continue to investigate the abilit of BPA, other genotoxic agents, and deficiencies in DNA repair to modulate DNA repair capacity, and I will characterize the consequences of these effects on human disease and disease progression. These short- and long-term studies will fulfill the strategic goals of the NIEHS by: 1) understanding of integrated effects of BPA, 2) connecting genotoxicity of BPA with human health implications, and 3) determining the molecular mechanism of the exposure response, and 4) training the next generation of environmental scientists.