Altered transport and epigenomic changes in maneb-potentiated neurotoxicity

描述（由申请人提供）：反复暴露于环境因素，如农药和金属，可以改变基因表达模式，潜在地导致对未来毒性损害的易感性增强。超过90%的帕金森病（PD）病例被认为是特发性的，流行病学表明农药与PD有关。具体来说，暴露于除草剂百草枯（PQ）和杀菌剂maneb （MB）与PD风险增加75-80%相关。此外，基因表达的表观基因组变化被认为在PD等神经退行性疾病中发挥作用。该候选人之前的NIEHS资助研究（F32 ES019821）表明，MB增强PQ神经毒性不仅仅是由于氧化应激的增强，而是一个复杂的机制，涉及MB对硫醇的修饰和PQ的氧化。其他基因表达数据显示，与PQ相比，MB显著改变了更多基因的表达。MB诱导了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，

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.