Combining synucleinopathy and mitochondrial deficits in a novel mouse model of Parkinsons disease

缺乏重现帕金森病（PD）进行性病理特征的动物模型阻碍了有效的疾病修饰疗法的发展。因此，本项目的目标是产生一种新的动物PD模型，以支持此类疗法的开发。临床数据显示，轴突终末衰竭和多巴胺能神经元的“死亡”可能先于PD患者黑质细胞体的丢失多年。这一漫长的过程在急性毒素诱导的PD动物模型中没有复制，这为这些模型的低预测能力提供了一个可能的解释。在小鼠中，enrailed 1基因的杂合缺失（En 1 +/-）导致轴突末端功能障碍和变性，最终导致黑质多巴胺能神经元的长期丧失。这一过程导致纹状体多巴胺缺乏，导致运动障碍。此外，这些变化与线粒体缺陷相关，类似于在一些PD患者中观察到的线粒体缺陷。尽管En 1 +/-小鼠模型具有所有优势，但它缺乏α-syn聚集。因此，我们假设线粒体缺陷（由于En 1的杂合丢失）与双侧注射致病性α-syn纤维（PFF）相结合，将协同产生高度相关的PD模型-En 1/SYN。我们进一步预测，En 1/SYN模型将表现出全面的PD相关行为缺陷（运动和非运动），并将模仿PD神经病理学。这种方法在小鼠中结合了PD的关键方面、多巴胺能系统的易感性、α-syn和PD病因的多因素性质，是创新的。支持我们的假设，我们的初步数据表明，PFFs诱导的α-syn病理学显著加剧了En 1的丢失。本研究的主要目的有两个：（1）通过向双侧纹状体注射致病性α-synuclein，触发PFF诱导的双侧α-syn病理。通过触发大脑两侧的病理学，新的小鼠模型预计将诱导强大的运动，更重要的是认知缺陷。我们将双侧注射重组纤维状α-syn（马继炎博士提供），测量α-syn-associated病理学的发展，然后在不同时间点评估小鼠的运动和非运动功能;（2）我们将通过在长期实验中比较我们的模型与人类PD的特征来验证En 1/SYN模型作为PD的模型，以及通过测试金标准PD治疗L-DOPA是否逆转由黑质多巴胺神经元损失和广泛的α-syn聚集诱导的运动缺陷。我们的研究有望产生一个强大的工具，可以加速症状和/或疾病修饰疗法的发展，以治疗运动和非运动PD。

The lack of animal models recreating the progressive pathology characteristic of Parkinson’s disease (PD) hinders the development of effective disease-modifying therapies. Thus, the goal of this project is to generate a new animal PD model that supports the development of such therapies. Clinical data revealed that axon terminal failure and “dying back” of dopaminergic neurons likely precede loss of substantia nigra cell bodies by many years in PD. This protracted process is not replicated in the acute toxin-induced animal models of PD, providing one possible explanation for the low predictive power of these models. The heterozygous deletion of the engrailed 1 gene in mice (En1+/–) results in axon terminal dysfunction and degeneration eventually leading to protracted loss of nigral dopaminergic neurons. This process causes striatal dopamine deficiency that leads to motor impairment. Furthermore, these changes are associated with mitochondrial deficits akin to those observed in some PD patients. Despite all the advantages that the En1+/– mouse model represents, it lacks α-syn aggregation. Thus, we hypothesize that mitochondrial deficits (due to heterozygous loss of En1) combined with bilateral injections of pathogenic α-syn fibrils (PFFs) will synergistically generate a highly relevant PD model – En1/SYN. We further predict that the En1/SYN model will exhibit a comprehensive set of PD-relevant behavioral deficits (both motor and non-motor) and will mimic PD neuropathology. This approach is innovative in combining, in mice, key aspects of PD, the susceptibility of the dopaminergic system, α-syn and the multifactorial nature of the etiology of PD. Supporting our hypothesis, our preliminary data show that PFFs-induced α-syn pathology is significantly exacerbated by the loss of En1. There are two major goals in this project: (1) We will trigger PFFs-induced α-syn pathology bilaterally by injecting pathogenic α-synuclein into both striata. By triggering the pathology on both sides of the brain the new mouse model is expected to induce robust motor, and more importantly cognitive deficits. We will bilaterally inject recombinant fibrillar α-syn (provided by Dr. Jiyan Ma), measure the development of α-syn-associated pathology, and then assess motor and non-motor function of mice at different time points; (2) We will validate the En1/SYN model as a model of PD, by comparing the features of our model to human PD in long-term experiments, as well as by testing if the gold-standard PD treatment L-DOPA reverses motor deficits induced by loss of nigral dopamine neurons and widespread α-syn aggregation. Our research is expected to generate a powerful tool, which can accelerate the development of symptomatic and/or disease-modifying therapies to treat motor and non-motor PD.