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

摘要α -突触核蛋白基因突变明确导致罕见的常染色体显性家族性帕金森病（PD）。α -突触核蛋白被认为在帕金森病的发病机制中起着核心作用，这是基于α -突触核蛋白基因的错义突变或三倍与家族性帕金森病的关联，以及α -突触核蛋白的纤维状形式作为帕金森病和其他α -突触核蛋白病的路易体的主要结构成分的鉴定。α -突触核蛋白的家族突变通过毒性功能获得机制导致帕金森病。通过产生以神经元特异性方式表达人类α -突触核蛋白致病性变体的帕金森病转基因小鼠模型，提供了功能获得机制的证据。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形成类似路易小体的细胞内包涵体的组合。然而，令人惊讶的是，黑质中的多巴胺能神经元却一直幸免。重要的是，由于黑质纹状体多巴胺能变性的明显缺失，目前的α -突触核蛋白转基因小鼠不能提供一个可靠的帕金森病模型，但可能代表有用的α -突触核蛋白病模型。α -突触核蛋白小鼠缺乏强大的pd样表型可能与选择用于转基因表达的启动子有关，因为其中许多启动子倾向于驱动小鼠脑干和脊髓内的强大转基因表达，导致运动神经元相关表型，而不是黑质纹状体途径相关表型。因此，在黑质纹状体多巴胺能神经元中特异性表达α -突触核蛋白致病变异将克服这一问题，并选择性地靶向帕金森病的主要神经元。为了在黑质纹状体多巴胺能神经元中表达α -突触核蛋白致病变异，将采用一种基于ccr - loxp的条件敲入策略，在酪氨酸羟化酶（TH）阳性的儿茶酚胺能神经元中产生特异性表达α -突触核蛋白变异（野生型和E46K突变型）的小鼠。这些小鼠将被评估为一种新的、健壮的帕金森病模型。在一些家族中，一种叫做-突触核蛋白的基因突变是帕金森病的罕见病因。了解这些基因突变是如何导致疾病的，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，从而我们可以更好地了解这种疾病，从而我们可能最终能够使用这些小鼠来测试新的治疗方法。

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.