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，人类接触是无处不在的。目前的双酚A研究已经单独评估了双酚A的遗传毒性，但没有研究其在各种环境DNA损伤剂(如食品添加剂溴酸钾或紫外线辐射)持续作用下对人体组织DNA的潜在损伤。为了解决这一关键差距，拟议的研究将检查双酚A与饮食和环境DNA损伤剂的共同暴露。初步结果表明，双酚A与外源氧化剂共暴露可提高细胞存活率，并抑制氧化DNA损伤的清除。这些研究将探讨双酚A和环境DNA损伤剂共同暴露会改变DNA修复能力并诱导双酚A基因毒性效应的假说。在指导的K99阶段，我将描述双酚A通过碱基切除修复去除DNA氧化损伤的作用。在DNA修复领域的领军人物塞缪尔·H·威尔逊博士的指导下，我将研究BPA用来抑制DNA损伤识别和/或OGG1 DNA糖基酶切除的机制，该酶负责清除氧化损伤损伤8-oxoG。研究将利用体内和体外测试来量化DNA链断裂，确定8-oxoG损伤的持久性，并确定OGG1活性下调的机制。这将建立双酚A改变DNA修复的工作假设，并为我继续作为一名独立研究员提供必要的培训。在R00阶段，我将通过检测BPA抑制碱基切除修复的特异性来扩展K99时期的研究。BPA与其他DNA损伤剂，如紫外线辐射的共同暴露，将被用来确定BPA是否专门抑制8-oxoG的去除。在这一阶段，我还将调查双酚A诱导的误码率抑制是否会导致基因组不稳定。我将确定病变的持久性是否会导致更多的突变，并将检查染色体重排，以确定病变的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与破坏性试剂组合对BER的影响。该项目的这一阶段将为我提供必要的技能基础，以便在研究型大学成为一名独立的环境健康调查员。作为一名独立的研究人员，我将继续调查双酚A、其他基因毒剂以及DNA修复缺陷对DNA修复能力的调节能力，并将表征这些影响对人类疾病和疾病进展的影响。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)了解双酚A的综合影响，2)将双酚A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.