Alpha-Synuclein Conditional Knock-in Mice as Novel Models of Parkinson's Disease

描述（由申请人提供）：α-突触核蛋白条件性敲入小鼠作为帕金森病的新模型摘要α-突触核蛋白基因中的突变明确地导致罕见的常染色体显性形式的家族性帕金森病（PD）。基于α-突触核蛋白基因的错义突变或三联体与家族性帕金森病的关联，以及鉴定出α-突触核蛋白的纤维形式为帕金森病和其他α-突触核蛋白病中路易体的主要结构组分，认为α-突触核蛋白在帕金森病的发病机制中起核心作用。α-突触核蛋白的家族性突变通过毒性功能获得机制引起帕金森病。通过产生帕金森病的转基因小鼠模型提供了功能获得机制的证据，该模型以神经元特异性方式表达人α-突触核蛋白的致病变体。这些转基因模型表现出运动功能障碍、选择性神经元变性和类似路易体的细胞内包涵体的形成的组合。然而，黑质中的多巴胺能神经元令人惊讶地一直幸免于难。重要的是，目前的α-突触核蛋白转基因小鼠由于明显缺乏黑质纹状体多巴胺能变性而不能提供稳健的帕金森病模型，但可能代表有用的α-突触核蛋白病模型。在α-突触核蛋白小鼠中缺乏稳健的PD样表型可能与用于转基因表达的启动子的选择有关，因为这些启动子中的许多倾向于在小鼠的脑干和脊髓内驱动稳健的转基因表达，导致运动神经元相关表型而不是黑质纹状体通路相关表型。因此，特异性地在黑质纹状体多巴胺能神经元内的α-突触核蛋白致病变体的稳健转基因表达将克服这个问题，并且将选择性地靶向帕金森病中受影响的主要神经元。为了实现α-突触核蛋白致病性变体在黑质纹状体多巴胺能神经元内的表达，将采用基于条件性Cre-loxP的敲入策略来产生在酪氨酸羟化酶（TH）阳性儿茶酚胺能神经元内特异性表达α-突触核蛋白变体（野生型和E46 K突变体）的小鼠。这些小鼠将被评估为一种新的、稳健的帕金森病模型。在一些家族中，一种叫做α-突触核蛋白的基因突变是导致帕金森病的罕见原因。了解这些基因突变如何导致疾病可能有助于开发旨在阻止，减缓或逆转疾病进展的新疗法。我们的研究旨在模拟小鼠中α-突触核蛋白突变形式的致病作用，以便准确地重现帕金森病的典型特征，以便我们能够更好地了解这种疾病，并且我们最终能够使用这样的小鼠来测试新的疗法。

DESCRIPTION (provided by applicant): Alpha-Synuclein Conditional Knock-in Mice as Novel Models of Parkinson's Disease Abstract Mutations in the alpha-synuclein gene unequivocally cause rare autosomal dominant forms of familial Parkinson's disease (PD). Alpha-synuclein is considered to play a central role in the pathogenesis of Parkinson's disease based upon the association of missense mutations or triplications of the alpha- synuclein gene with familial Parkinson's disease, as well as the identification of fibrillar forms of alpha-synuclein as a major structural component of Lewy bodies in Parkinson's disease and other alpha-synucleinopathies. Familial mutations in alpha-synuclein cause Parkinson's disease through a toxic gain-of-function mechanism. Evidence for a gain-of-function mechanism has been provided through the generation of transgenic mouse models of Parkinson's disease that express pathogenic variants of human alpha-synuclein in a neuronal-specific manner. These transgenic models exhibit combinations of motoric dysfunction, selective neuronal degeneration, and the formation of intracellular inclusions resembling Lewy bodies. However, dopaminergic neurons in the substantia nigra are surprisingly yet consistently spared. Importantly, current alpha-synuclein transgenic mice do not provide a robust model of Parkinson's disease due to the conspicuous absence of nigrostriatal dopaminergic degeneration but may instead represent useful alpha-synucleinopathy models. The lack of a robust PD-like phenotype in alpha-synuclein mice may relate to the choice of promoter employed for transgene expression, since many of these tend to drive robust transgene expression within the brainstem and spinal cord of mice leading to motor neuron-related phenotypes rather than nigrostriatal pathway-related phenotypes. Thus, robust transgenic expression of alpha-synuclein pathogenic variants specifically within nigrostriatal dopaminergic neurons would overcome this problem and would selectively target the principal neurons affected in Parkinson's disease. To achieve expression of alpha-synuclein pathogenic variants within nigrostriatal dopaminergic neurons, a conditional Cre-loxP-based knock-in strategy will be employed to generate mice that express alpha-synuclein variants (wild-type and E46K mutant) specifically within tyrosine hydroxylase (TH)-positive catecholaminergic neurons. These mice will be evaluated as a novel, robust model of Parkinson's disease. Mutations in a gene called alpha-synuclein are a rare cause of Parkinson's disease in some families. Understanding how these genetic mutations cause disease may allow the development of novel therapies aimed at halting, slowing or reversing disease progression. Our studies aim to model the pathogenic effects of mutant forms of alpha-synuclein in mice in order to accurately recreate the typical features of Parkinson's disease so that we can better understand this disease, and so that we may be able to ultimately use such mice to test novel therapies.