A Mouse Model of RNA-induced Neurotoxcity

含有长CUG重复序列的RNA转录本的毒性，一种疾病发病的新机制， 最近在强直性肌营养不良1型(DM1)中被描述，这是成人发病的最常见形式 肌肉营养不良症。CUG扩张导致细胞毒性的确切机制尚不清楚， 尽管可能涉及对剪接的错误调控。我们的小组最近发现了一种常染色体显性遗传 疾病，亨廷顿病样2(HDL2)，临床和病理特征几乎与 亨廷顿氏病(HD)，一种无情的进行性成人神经退行性疾病。就像HD一样， HDL2是由CAG/CTG扩展突变引起的。令我们惊讶的是，HDL2的发病机制，如 DM1和HD不同，似乎至少部分是由于含有以下成分的RNA转录本的毒性作用 长CUG重复。为了验证未翻译的CUG扩增可导致神经毒性的假设 哺乳动物的大脑，我们建议产生一只转基因小鼠，专门表达一种扩展的 Cug在大脑中重复。在特定的目标1中，我们将使用一种 包含带有正常CTG或扩展CTG的JPH3短片段的不可翻译构造 在大脑特异性PrP启动子的控制下重复。在特定目标2中，行为、运动和 将检查这些小鼠的病理表型。在具体目标3中，CUG的具体特点 将在小鼠身上检查重复扩张性疾病，重点是RNA焦点和蛋白质 聚合。我们预测，扩展的CUG重复序列将导致神经毒性，这在运动中很明显 行为和神经病理学。如果这一预测是正确的，那么这里产生的老鼠将变得无价 解剖DM1、HD和HDL2致病途径的工具。找准致病穴位 这些疾病的融合可能为合理治疗的发展提供新的线索。

Toxicity of RNA transcripts containing long CUG repeats, a novel mechanism of disease pathogenesis, was recently described in myotonic dystrophy type 1 (DM1), the most common form of adult onset muscular dystrophy. The precise mechanism by which CUG expansions lead to cell toxicity is unclear, though misregulation of splicing may be involved. Our group recently identified an autosomal dominant disorder, Huntington's disease-like 2 (HDL2), with clinical and pathological features almost identical to Huntington's disease (HD), a relentlessly progressive adult onset neurodegenerative disorder. Like HD, HDL2 is caused by a CAG/CTG expansion mutation. To our surprise, the pathogenesis of HDL2, like DM1 and unlike HD, appears to arise at least in part from the toxic effect of RNA transcripts containing long CUG repeats. To test the hypothesis that untranslated CUG expansions can lead to neurotoxicity in the mammalian brain, we propose to generate a transgenic mouse specifically expressing an expanded CUG repeat in the brain. In Specific Aim 1, we will generate CUG transgenic mice, using an untranslatable construct that contains a short fragment of JPH3 with either a normal or an expanded CTG repeat under the control of the brain-specific PrP promoter. In Specific Aim 2, the behavioral, motoric, and pathological phenotype of these mice will be examined. In Specific Aim 3, specific characteristics of CUG repeat expansion diseases will be examined in the mice, with an emphasis on RNA foci and protein aggregation. We predict that the expanded CUG repeat will lead to neurotoxicity, evident in motor behavior and neuropathology. If this prediction is correct, the mice generated here will become invaluable tools for dissecting the pathogenic pathways of DM1, HD, and HDL2. Finding the points of pathogenic convergence in these diseases may provide novel leads for the development of rational therapeutics.