Altered transport and epigenomic changes in maneb-potentiated neurotoxicity

描述（由申请人提供）：反复暴露于环境因子，如农药和金属，可改变基因表达模式，可能导致对未来毒性损伤的易感性增强。超过90%的帕金森病（PD）病例被认为是特发性的，流行病学表明农药参与了PD。具体而言，接触除草剂百草枯（PQ）和杀真菌剂代森锰（MB）与PD风险增加75-80%相关。此外，假定基因表达的表观基因组变化在神经退行性疾病如PD中起作用。该候选人之前的NIEHS资助研究（F32 ES 019821）证明，MB增强PQ神经毒性不仅仅是由于氧化应激增强，而是一种涉及MB巯基修饰和PQ氧化的复杂机制。额外的基因表达数据表明，MB显着改变了更多的基因的表达相比，PQ。MB诱导4种不同的氨基酸转运蛋白和2种金属转运蛋白。特别有趣的是，阿拉， 与对照相比，MB和PQ+MB诱导的Ser-、Cys-偏好转运蛋白-1（ASCT-1（Slc 1a 4））和质子偶联二价金属离子转运蛋白（LSH（Slc 11 a1））超过2倍。该K99/R 00职业发展奖提案的工作假设是，长期暴露于MB会增强PQ介导的多巴胺能神经元神经变性，这是由于修饰的氨基酸转运蛋白表达、金属介导的氧化应激和表观基因组变化导致PQ摄取增加所致。为了实现这一点，将使用4个特定目标（2个指导，2个独立），包括体外和体内模型。在特定目标1（K99指导阶段）中，将采用体外和体内模型来确定PQ神经毒性的增强是否归因于MB介导的ASCT-1和LSH诱导。具体目标2（K99指导阶段）将研究与多巴胺代谢相关的基因甲基化是否在机制上参与MB增强的PQ神经毒性。在特定目标3（R 00独立阶段）中提出的研究将探索长期农药暴露引起的组蛋白H3甲基化和乙酰化的改变。最后，特定目标4（R 00独立阶段）将研究DNA甲基化组在长期农药暴露下的整体变化。该项目旨在进一步发展候选人的研究计划，并通过表观基因组学研究将环境影响与疾病联系起来，实现NIEHS的战略目标，并培养下一代环境科学家。拟议的研究将满足这些目标，并促进独立研究事业的发展。 公共卫生相关性：农药暴露被认为有助于帕金森病的发展，影响全球1%的人口。候选人认为，影响是由于农药的组合而发生的，其中一种农药可以通过增加运输和改变基因表达来增强第二种农药的毒性。本项目旨在验证这一假设。

DESCRIPTION (provided by applicant): Repeated exposure to environmental agents, such as pesticides and metals, can alter gene expression patterns, potentially resulting in enhanced susceptibility to future toxic insults. With greater than 90% of Parkinson's disease (PD) cases considered idiopathic, epidemiology has indicated the involvement of pesticides in PD. Specifically, exposures to the herbicide paraquat (PQ) and the fungicide maneb (MB) are associated with a 75-80% increased risk of PD. Additionally, epigenomic changes in gene expression are postulated to play a role in neurodegenerative disorders like PD. The candidate's previous NIEHS funded research (F32 ES019821) demonstrated that MB-potentiation of PQ neurotoxicity was not simply due to enhanced oxidative stress, but a complex mechanism involving thiol-modification by MB and oxidation by PQ. Additional gene expression data show that MB significantly altered the expression of more genes compared to PQ. MB induced 4 different amino acid transporters and 2 metal transporters. Of particular interest, Ala-, Ser-, Cys- preferring transporter-1 (ASCT-1 (Slc1a4)) and proton coupled, divalent metal ion transporter (LSH (Slc11a1)) were induced greater than 2-fold by MB and PQ+MB compared to control. The working hypothesis for this K99/R00 Career Development Award proposal is that long-term exposure to MB potentiates PQ-mediated neurodegeneration of dopaminergic neurons caused by increased uptake of PQ due to modified amino acid transporter expression, metal-mediated oxidative stress and changes in the epigenome. To accomplish this, 4 specific aims (2 mentored, 2 independent) consisting of in vitro and in vivo models will be used. In Specific Aim 1 (K99 mentored phase), both in vitro and in vivo models will be employed to determine if potentiation of PQ neurotoxicity is due to MB-mediated induction of ASCT-1 and LSH. Specific Aim 2 (K99 mentored phase) will study if methylation of genes associated with dopamine metabolism is mechanistically involved in MB- potentiated PQ neurotoxicity. Research proposed in Specific Aim 3 (R00 independent phase) will explore alterations in histone H3 methylation and acetylation caused by long term pesticide exposure. Lastly, Specific Aim 4 (R00 independent phase) will investigate global alterations in the DNA methylome in response to long term pesticide exposure. This project is designed to further develop the candidate's research program and fulfill strategic goals of the NIEHS by connecting environmental influences to disease through the study of epigenomics and to train the next generation of environmental scientists. The proposed research will meet these goals and foster the development of an independent research career. Public Health Relevance: Pesticide exposure is believed to contribute to the development of Parkinson's disease, which affects 1% of the worldwide population. The candidate believes that effects occur due to a combination of pesticides, where one pesticide can enhance the toxicity of a second pesticide via increased transport and altered gene expression. This project is designed to test this hypothesis.