DJ-1 in Astrocyte-Mediated Neuroprotection Against Complex I Inhibitors

描述（由申请人提供）：帕金森病（PD）以多脑区进行性神经元丧失为特征。特别受影响的是中脑致密黑质（SNpc）。在帕金森病中，该区域显示多巴胺能神经元变性和线粒体呼吸链复合体I活性不足。1-甲基-4-苯基-1,2,3,6-四氢吡啶（MPTP）是一种复合物I抑制剂，通过选择性杀死SNpc多巴胺能神经元导致人类帕金森病。在动物模型中，包括鱼藤酮在内的几种杀虫剂也选择性地抑制复合体I并导致SNpc多巴胺能神经变性。人类流行病学研究现已将农药暴露与帕金森病风险增加联系起来。最近的一项研究与职业接触鱼藤酮有关。因此，环境毒物（农药）暴露导致PD中所见的复合物I缺乏是合理的，并且这一机制是疾病发生和/或进展的核心。我们的研究目标是确定大脑对复杂i抑制环境毒物诱导的神经变性所采用的自然保护策略。最终，我们希望利用这些机制来开发针对PD的新型疾病修饰疗法。我们最近的工作已经确定了DJ-1在星形胶质细胞中的过表达作为体外抗复合物i抑制农药的神经保护机制。这一过程似乎涉及星形细胞释放因子，并且可能与PD特别相关，因为(1)反应性星形细胞在散发性PD中过度表达DJ-1，(2)消除DJ-1表达的突变导致家族性PD。因此，我们假设星形细胞DJ-1在人脑中的过度表达可能代表了对PD的自然神经保护尝试。如果这是真的，这一过程可能作为疾病改善治疗的目标。为了在完整的大脑中模拟这种可能性，我们将评估星形细胞DJ-1过表达的能力，以减少转基因小鼠mptp诱导的SNpc多巴胺能神经变性（目的1）。我们将利用行为学、免疫组织化学和生化分析对我们实验室最近开发的新型小鼠进行研究，这些小鼠在胶质纤维酸性蛋白启动子的控制下，在星形胶质细胞中选择性地过度表达DJ-1。我们还将评估慢病毒介导的星形细胞DJ-1过表达对大鼠鱼藤酮的类似作用（目的2）。在每种情况下，我们假设星形胶质细胞DJ-1的过表达将增强星形胶质细胞介导的神经保护，以对抗复合物I的抑制。Aim 2还将测试一种针对农药诱导的神经变性的实验性转化基因治疗方法。在我们的最终目标中，我们将使用分析化学方法来鉴定在我们的细胞培养模型中携带神经保护活性的dj -1调节的星形胶质细胞释放的可溶性因子。这些因素或它们所使用的机制也可能产生针对农药诱导的神经变性和PD的新治疗策略。

DESCRIPTION (provided by applicant): Parkinson's disease (PD) is characterized by progressive neuronal loss in multiple brain regions. Particularly affected is the substantia nigra pars compacta (SNpc) of the midbrain. In PD, this region shows degeneration of dopaminergic neurons and deficient mitochondrial respiratory chain complex I activity. 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), a complex I inhibitor, has caused human parkinsonism by selectively killing SNpc dopaminergic neurons. Several pesticides, including rotenone, also selectively inhibit complex I and cause SNpc dopaminergic neurodegeneration in animal models. Human epidemiological studies have now linked pesticide exposure to an increased risk for PD. One recent study implicated occupational exposure to rotenone. It is therefore plausible that environmental toxicant (pesticide) exposure causes the complex I deficiency seen in PD, and that this mechanism is central to disease initiation and/or progression. Our research goal is to identify natural protective strategies employed by the brain against neurodegeneration induced by complex I-inhibiting environmental toxicants. Ultimately, we hope to exploit these mechanisms to develop novel disease-modifying therapies against PD. Our recent work has identified DJ-1 over-expression in astrocytes as a neuroprotective mechanism against complex I-inhibiting pesticides in vitro. This process appears to involve astrocyte-released factors, and may be particularly relevant to PD because (i) reactive astrocytes over-express DJ-1 in sporadic PD and (ii) mutations that eliminate DJ-1 expression cause familial PD. Thus, we hypothesize that astrocytic DJ-1 over-expression in the human brain may represent a natural neuroprotective attempt against PD. If true, this process may be targetable for augmentation as disease-modifying therapy. To model this possibility in the intact brain, we will assess the capacity of astrocytic DJ-1 over-expression to reduce MPTP-induced SNpc dopaminergic neurodegeneration in transgenic mice (Aim 1). This will be studied using behavioral, immunohistochemical, and biochemical analyses in novel mice, recently developed in our lab, that over- express DJ-1 selectively in astrocytes under control of the glial fibrillary acidic protein promoter. We will also assess the capacity of lentivirus-mediated astrocytic DJ-1 over-expression to perform similarly against rotenone in rats (Aim 2). In each case, we hypothesize that astrocytic DJ-1 over-expression will augment astrocyte-mediated neuroprotection against complex I inhibition. Aim 2 will also test an experimental translational gene therapy approach against pesticide-induced neurodegeneration. In our final Aim we will use analytical chemistry methods to identify the DJ-1-modulated, astrocyte-released soluble factor(s) that carry the neuroprotective activity in our cell culture model. These factors, or the mechanisms they employ, may also generate novel therapeutic strategies against pesticide-induced neurodegeneration and PD.