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

描述(申请人提供)：帕金森病(PD)的特征是多个脑区进行性神经元丢失。尤其受影响的是中脑的黑质致密部(SNPC)。在帕金森病患者，这个区域表现为多巴胺能神经元的变性和线粒体呼吸链复合体I活性的缺乏。1-甲基-4-苯基-1，2，3，6-四氢吡啶(MPTP)是一种复杂的I类抑制剂，通过选择性地杀死SNPC多巴胺能神经元而引起人类帕金森病。包括鱼藤酮在内的几种杀虫剂也选择性地抑制复合体I，并在动物模型中引起SNPC多巴胺能神经变性。人类流行病学研究现已将接触杀虫剂与帕金森病风险增加联系在一起。最近的一项研究表明，职业性接触鱼藤酮。因此，环境毒物(农药)暴露可能导致帕金森病患者出现复杂的碘缺乏，并且这一机制是疾病启动和/或进展的中心。我们的研究目标是确定大脑使用的天然保护策略，以防止复杂的I-抑制环境毒物引起的神经退化。最终，我们希望利用这些机制来开发针对帕金森病的新的疾病修正疗法。我们最近的工作证实，在体外，DJ-1在星形胶质细胞中的过度表达是一种对复杂的I-抑制杀虫剂的神经保护机制。这一过程似乎涉及星形胶质细胞释放的因子，可能与PD特别相关，因为(I)反应性星形胶质细胞在散发性PD中过度表达DJ-1，(Ii)消除DJ-1表达的突变导致家族性PD。因此，我们假设人脑中星形细胞DJ-1的过度表达可能代表了对帕金森病的自然神经保护尝试。如果是真的，这一过程可能是有针对性的，可以扩大为疾病修正疗法。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过度表达减少MPTP诱导的转基因小鼠SNPC多巴胺能神经变性的能力(目标1)。这将通过我们实验室最近开发的新型小鼠的行为、免疫组织化学和生化分析来研究，这些小鼠在胶质纤维酸性蛋白启动子的控制下选择性地在星形胶质细胞中过度表达DJ-1。我们还将评估慢病毒介导的星形胶质细胞DJ-1过度表达在大鼠身上对抗鱼藤酮的能力(目标2)。在每种情况下，我们都假设星形胶质细胞DJ-1的过度表达将增强星形胶质细胞介导的神经保护，对抗复合体I的抑制。Aim 2还将测试一种针对农药诱导的神经退化的实验性翻译基因治疗方法。在我们的最终目标中，我们将使用分析化学方法来鉴定DJ-1调节的、星形胶质细胞释放的可溶性因子(S)，它在我们的细胞培养模型中具有神经保护活性。这些因素或它们所采用的机制也可能产生针对农药诱导的神经变性和帕金森病的新的治疗策略。

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.