Antisense oligonucleotides for the treatment of spinocerebellar ataxia type 2

描述(申请人提供)：神经退行性疾病是一个不断增加的社会和经济负担，世卫组织估计，到2040年，它们将取代癌症成为第二大死亡原因。在神经退行性疾病的研究中，已经发现了大量的通路，但它们与各自的人类疾病的直接和主要相关性一直很难证明，而且针对通路的定位仍然困难。这项拟议的工作将确定一种治疗脊髓小脑性共济失调2型(SCA2)的方法，这是一种遗传性神经退行性疾病，影响小脑浦肯野神经元(PNS)和小脑、脑干和大脑的其他神经元。SCA2的原因是ATXN2基因的CAG功能增强，导致ataxin-2中的多聚谷氨酰胺(PolyQ)的扩张。我们的目标是鉴定能够降低ATXN2表达的反义寡核苷酸(ASO)。我们的理论基础是基于对模式生物和人类的观察，结果表明，更高剂量的突变等位基因/蛋白会恶化疾病严重程度，即使在小鼠出现症状后，啮齿动物中突变PolyQ蛋白表达的下调也会逆转临床表现。此外，在小鼠中完全敲除ATXN2不会导致神经退化或过早死亡。这项研究的优点得到了多发性ASO临床试验和正在进行的测试ASOS治疗肌萎缩侧索硬化症(ALS)和脊髓性肌萎缩症(SMA)的临床试验的积极结果的支持。可行性是基于已建立的资源，包括体外鉴定的铅ASO和具有晚发型进行性运动表型的具有良好特征的人-BAC转基因小鼠模型。提出了三个具体目标：1)从我们已经在ASO初步筛查中确定的15个ASO导联中，确定4个最有效地降低ATXN2表达的ASO导联；2)测试ASO导联以改善包括维持神经胶质健康的指示的生化内表型；以及3)在SCA2小鼠BAC模型中测试两个最有效的ASO以改善运动表型。这项拟议的工作将为神经退行性疾病的治疗开辟新的天地，因为它证明了用反义寡核苷酸靶向显性作用突变的多聚Q基因的可行性。

DESCRIPTION (provided by applicant): Neurodegenerative diseases represent an ever-increasing societal and economic burden with WHO estimates indicating that they will replace cancer as the 2nd leading cause of death by 2040. In neurodegenerative disease research, a wealth of pathways has been uncovered, but their direct and primary relevance to the respective human disease has been difficult to prove and targeting of pathways has remained difficult. The proposed work will identify a treatment for spinocerebellar ataxia type 2 (SCA2), a hereditary neurodegenerative disease affecting cerebellar Purkinje neurons (PNs) and other neurons in the cerebellum, brainstem and cerebrum. The cause of SCA2 is a gain-of-function CAG expansion in the ATXN2 gene resulting in an expanded polyglutamine (polyQ) in ataxin-2. Our objective is identification of antisense oligonucleotides (ASOs) that lower ATXN2 expression. Our rationale is based on observations in model organisms and humans indicating that higher dosages of the mutant allele/protein worsen disease severity and that down-regulation of mutant polyQ protein expression in rodents reverses clinical manifestations even after mice have become symptomatic. Additionally, complete knock-out of ATXN2 in mice does not cause neurodegeneration or premature death. Merit for this study is supported by positive results in clinical trials for multiple ASOs, and ongoing clinical trials to test ASOs for the treatment of amyotrophic lateral sclerosis (ALS) and spinal muscular atrophy (SMA). The feasibility is based on established resources including lead ASOs identified in vitro and a well-characterized human-BAC transgenic mouse model with late onset progressive motor phenotypes. Three specific aims are proposed: 1) Identification of the 4 most effective ASOs for lowering ATXN2 expression, from 15 lead ASOs that we have already identified in a preliminary ASO screen, 2) testing the ASO leads for amelioration of a biochemical endophenotype that includes indication of maintained glial health, and 3) testing the two most effective ASOs for ameliorating a motor phenotype in an SCA2 mouse BAC model. The proposed work will break new ground for treatment of neurodegenerative diseases by demonstrating feasibility of targeting dominant-acting mutated polyQ genes with antisense oligonucleotides.