Novel Mechanisms of Pesticide-Induced Neurotoxicity

摘要 环境暴露于神经毒性杀虫剂已日益被认为是一种关键的致病因素 散发性帕金森病(PD)的致病因素。尽管已经建立了联系，但破译神经毒理学 与慢性农药暴露相关的机制及其在帕金森病发病机制中的作用 很有挑战性。因此，我们的研究方案意在探索一种新的环境研究范式 用动物模型研究农药暴露中组蛋白乙酰化的神经毒理学 农药的神经毒性。在各种杀虫剂中，暴露于线粒体损伤的神经毒性 杀虫剂，如鱼藤酮，已被认为与帕金森病的病因有关。从机理上讲，接触鱼藤酮和 另一种相关的杀虫剂吡达本抑制线粒体复合体-1并损害蛋白酶体功能。 神经细胞。多巴胺能神经元已被证明对鱼藤酮的诱导非常脆弱。 神经毒性。在研究线粒体损伤的农药诱导的蛋白酶体功能障碍时 神经毒性，我们意外地发现鱼藤酮和吡虫啉诱导的蛋白酶体抑制 导致主要的组蛋白乙酰转移酶CBP(CREB结合蛋白)的积累， 这进一步促进了组蛋白H3和H4的乙酰化，促进了多巴胺能神经元的凋亡 神经元。由于组蛋白的超乙酰化正在成为一种能够产生 染色质重塑引起的基因表达谱的长期变化，我们建议探索这一新的 慢性线粒体黑质多巴胺能神经元损伤的分子事件机制 损害农药诱导的神经毒性模型。这项工作将通过开展以下工作来完成 具体目标：1)定位多巴胺能神经元核心组蛋白H3和H4的高乙酰化位点 线粒体抑制神经毒性农药暴露后的培养，II)表征细胞机制 通过检测不同亚型对农药诱导组蛋白H3和H4超乙酰化的影响 组蛋白乙酰转移酶(HATS)和组蛋白脱乙酰酶(HDACs)，以及iii)决定组蛋白乙酰化 慢性鱼藤酮或吡虫啉农药神经毒性动物模型及其进展模式 线粒体功能障碍转基因帕金森病小鼠模型，证实乙酰化模式的变化 和HAT/HDAC在帕金森病患者脑组织中的稳态，并明确了组蛋白的功能意义 与神经毒性农药诱导的神经元变性有关的高乙酰化依赖信号。蜂窝， 将使用分子和神经化学方法来描述这些目标。总的来说，建议的 这项研究代表了农药神经毒理学研究的一种新方法，因为这项工作将提供 全面了解与环境相关的组蛋白超乙酰化机制 黑质多巴胺能神经元毒性与环境相关性帕金森病的发病机制。

Abstract Environmental exposure to neurotoxic pesticides has been increasingly recognized as a key etiological factor of sporadic Parkinson’s disease (PD). Despite the established link, deciphering the neurotoxicological mechanisms associated with chronic pesticide exposure and its role in the etiopathogenesis of PD has been challenging. Thus, our research proposal intends to explore a novel paradigm in environmental neurotoxicology by studying the acetylation of histone proteins during pesticide exposure using animal models of pesticide neurotoxicity. Among various classes of pesticides, exposure to mitochondria-impairing neurotoxic pesticides, e.g., rotenone, has been linked to the etiology of PD. Mechanistically, exposure to rotenone and another related pesticide, pyridaben, inhibits mitochondrial complex-1 and impairs proteasomal function in neuronal cells. Dopaminergic neurons have been shown to be highly vulnerable to rotenone-induced neurotoxicity. While studying proteasomal dysfunction in mitochondria-impairing pesticide-induced neurotoxicity, we unexpectedly discovered that rotenone- and pyridaben-induced proteasomal inhibition resulted in the accumulation of the major histone acetyltransferase enzyme CBP (CREB-binding protein), which further contributed to acetylation of histones H3 and H4 to promote apoptotic cell death in dopaminergic neurons. Since hyperacetylation of histones is emerging as a key molecular mechanism capable of producing long-term changes in gene expression profiles due to chromatin remodeling, we propose to explore this novel mechanism in the molecular events underlying nigral dopaminergic neuronal damage in chronic mitochondria- impairing pesticide-induced neurotoxicity models. This work will be accomplished by pursuing the following specific objectives: i) Map the hyperacetylation sites of core histones H3 and H4 in dopaminergic neuronal cultures following mitochondria-inhibiting neurotoxic pesticide exposure, ii) Characterize cellular mechanisms of pesticide-induced hyperacetylation of histones H3 and H4 by examining the contributions of various isoforms of histone acetyltransferases (HATs) and histone deacetylases (HDACs), and iii) Determine histone acetylation pattern in chronic rotenone or pyridaben animal models of pesticide neurotoxicity as well as in a progressive mitochondrial dysfunction-induced transgenic mouse model of PD, confirm the changes in acetylation patterns and HAT/HDAC homeostasis in human PD brain tissues, and define the functional significance of histone hyperacetylation-dependent signaling relevant to neurotoxic pesticide-induced neuronal degeneration. Cellular, molecular and neurochemical approaches will be used to delineate these objectives. Collectively, the proposed study represents a novel approach in pesticide neurotoxicological research since the work will provide a comprehensive understanding of the histone hyperacetylation mechanisms pertaining to environmentally- induced nigral dopaminergic neuronal toxicity as it relates to the etiopathogenesis of environmentally-linked PD.