Pesticide Interactions in LRRK2 Transgenic Models

描述（由申请人提供）：本项目的总体目标是评估神经毒物和衰老作为应激源促进帕金森病（PD）及相关神经退行性疾病病理生理的作用。我们的计划是利用一种实验范式，将新的转基因小鼠模型与神经毒物暴露方案和衰老相结合，目的是阐明可以解释农药与帕金森病相关蛋白质之间相互作用的特定机制。要测试的主要压力源包括可能使人类大量接触的环境因素，因此这些研究与一般公众健康高度相关。具体来说，我们将研究LRRK2蛋白作为神经退行性疾病与帕金森病之间的共同机制联系。lrrk2相关的PD通常模拟散发性PD；然而，即使在具有相同突变的家族中，蛋白质的某些突变也会导致临床和病理表型的显着多形性，从没有黑质细胞丢失到明显的tau病理。事实上，lrrk2相关综合征表现出与PD和相关疾病相关的所有病理特征；因此，这种蛋白质被称为神经退行性疾病的“罗塞塔石”。LRRK2突变也与外显率有关，外显率与发病年龄有关，发病年龄从典型的散发性PD到晚至10岁。这表明，某些携带突变的个体可能不会完全表现出突变（即疾病发展）。本提案的驱动假设是，环境暴露和/或衰老可能需要确定lrrk2相关疾病的病理表型。为了验证这一假设，我们将给两种人类LRRK2转基因小鼠（LRRK2过表达者和G2019S突变表达者）和野生型小鼠单独或联合施用百草枯或二乙基二硫代氨基甲酸酯。在Aim 1中，我们将通过评估运动活性、黑质多巴胺能细胞数量、纹状体多巴胺水平和神经胶质激活来研究有毒物质和/或衰老对LRRK2转基因小鼠黑质纹状体易损性的影响。在目标2中，我们将评估转基因和野生型小鼠中可能导致农药暴露后退行性事件的有毒蛋白质物种（即tau和1-syn）。第三个目的是评估lrrk2相关帕金森病的退化机制，以及不同的途径是否因衰老和毒物暴露而被激活。该建议假设帕金森病的多因素病因学，并提供了一个独特的机会来系统地评估这些因素对新型转基因帕金森病模型的影响。公共卫生相关性：越来越多的证据表明，环境暴露可以影响帕金森病（PD）和神经退行性疾病的发展。LRRK2的突变可能导致类似散发性PD的综合征，但同样的突变，即使在一个家族中，也可能导致不同的结果，在一个成员中表现为典型的PD，但在另一个成员中表现为具有认知障碍等特征的不同PD相关疾病。这些发现表明，暴露于环境因素可能影响在lrrk2相关疾病中发展的pd相关综合征。在本提案中，我们将测试暴露于神经毒物（包括那些可能对人类有重大暴露的神经毒物）是否可以决定人类LRRK2表达改变的转基因小鼠的行为和病理特征。这些研究可能导致：(i)更好地了解导致LRRK2患者病理发展的机制，但也（ii）深入了解暴露于特定毒物是否可以影响甚至决定特定帕金森综合征的发展，包括散发性帕金森病。

DESCRIPTION (provided by applicant): The overall objective of this project is to evaluate the role of neurotoxicants and aging as stressors that promote pathophysiology of Parkinson's disease (PD) and related neurodegenerative diseases. Our plan for this proposal is to utilize an experimental paradigm that combines new transgenic mouse models with neurotoxicant exposure regimens and aging, with a goal of elucidating specific mechanisms that could explain interactions between pesticides and proteins implicated in parkinsonism. The primary stressors to be tested include environmental agents that have the potential for significant human exposure, making the studies highly relevant to the general public health. Specifically, we will investigate the LRRK2 protein as a common mechanistic link between neurodegenerative conditions with parkinsonism. LRRK2-related PD typically mimics sporadic PD; yet certain mutations in the protein result in remarkable pleomorphism in clinical and pathological phenotype, ranging from no nigral cell loss to frank tau pathology, even within families with the same mutation. Indeed, LRRK2-related syndromes exhibit all the pathological hallmarks associated with PD and related disorders; consequently, this protein has been called the "Rosetta stone" for neurodegenerative disease. LRRK2 mutations are also associated with penetrance that is age-dependent with age of onset ranging from that of typical sporadic PD to as late as the tenth decade. This suggests that full manifestation of the mutation (i.e. disease development) may not occur in some individuals carrying the mutation. The driving hypothesis in this proposal is that environmental exposure and/or aging may be required for determining the pathological phenotype in LRRK2-related disorders. To test this hypothesis, we will administer paraquat or diethyldithiocarbamate, alone and in combination, to two lines of human LRRK2 transgenic mice (LRRK2 overexpressors and G2019S mutant expressors) and wildtype littermates. The effect of toxic agents and/or aging on nigrostriatal vulnerability in LRRK2 transgenic mice will be examined in Aim 1, by evaluating locomotor activity, nigral dopaminergic cell number, striatal dopamine levels and glial activation. In Aim 2, we will assess the toxic protein species that likely contribute to degenerative events following pesticide exposure (i.e. tau and 1-syn), in both transgenic and wildtype mice. The third aim will evaluate the mechanisms of degeneration underlying LRRK2-related parkinsonism and whether distinct pathways are activated as a consequence of aging and toxicant exposure. This proposal assumes a multi-factorial etiology of parkinsonism and provides a unique opportunity to methodically evaluate the impact of each of these factors in novel transgenic models of PD. PUBLIC HEALTH RELEVANCE: Accumulating evidence indicates that environmental exposures can influence the development of Parkinson's disease (PD) and neurodegenerative disorders. Mutations in LRRK2 can cause a syndrome that mimics sporadic PD, but the same mutation, even within a single family, can result in various outcomes, presenting as typical PD in one member, but a different PD-related disorder with features such as cognitive impairment, in another. These findings suggest that exposure to environmental agents may affect the PD-related syndrome that develops in LRRK2-related disorders. In this proposal, we will test whether exposure to neurotoxicants (including those that have the potential for significant human exposures) can determine the behavioral and pathological features that develop in transgenic mice with altered human LRRK2 expression. Such studies may lead: (i) a better understanding of the mechanisms that contribute to the development of pathology in LRRK2 patients, but also (ii) provide insight into whether exposure to a specific toxicant can influence or even determine the development of a particular parkinsonian syndrome, including sporadic PD.