Contribution of RAN proteins to HD, SCA3 other CAG.CTG expansion diseases

项目摘要 由于我们在2011年发现了重复相关的非ATG（RAN）RAN翻译，我们和 其他人已经表明RAN蛋白在九种不同的扩张性疾病中积累。这些 蛋白质，其可以从正义和反义扩增转录物表达， 在疾病相关的人体组织中积累，包括脊髓小脑共济失调8型（SCA8） 和亨廷顿病（HD）。我们现在有证据表明聚丝氨酸和聚亮氨酸RAN蛋白 在脊髓小脑共济失调组（SCA1、2、3、6和7）中积累，其中CAG·CTG 扩增突变位于polyGln开放阅读框中。此外，我们还有 开发了AAV和小分子方法来抑制RAN翻译。我们将会用这些 工具和遗传学方法来测试我们的中心假设，即RAN蛋白病理学是一种 编码CAG·CTG的多聚谷氨酰胺扩增障碍共有的共同特征， 抑制PKR通路将降低RAN蛋白水平并减轻疾病。 我们将在三个具体目标中讨论我们的中心假设：（1）为了检验假设， RAN蛋白导致脊髓小脑共济失调（SCA），由多聚谷氨酰胺编码 CAG·CTG重复扩增突变。(2)为了检验SCA和HD RAN 蛋白质是有毒的，PKR抑制将降低RAN蛋白质水平并改善细胞毒性。 HD和SCA3 iPSC衍生的细胞中的表型（3）：为了检验RAN蛋白表达的假设， 有助于HD和SCA3表型在小鼠中独立的聚谷氨酰胺的影响，使用遗传 和药理学方法。这些具体目标将决定 RAN蛋白对HD、SCA3和CAG·CTG重复扩增障碍的贡献， 将PKR抑制表征为这一大类 毁灭性的重复扩张疾病。

Project Summary Since we discovered repeat associated non-ATG (RAN) RAN translation in 2011, we and others have shown that RAN proteins accumulate in nine different expansion disorders. These proteins, which can be expressed from both sense and antisense expansion transcripts, accumulate in disease-relevant human tissues including spinocerebellar ataxia type 8 (SCA8) and Huntington disease (HD). We now have evidence that polySer and polyLeu RAN proteins accumulate in a group of spinocebellar ataxias (SCA1, 2, 3, 6 and 7) in which the CAG·CTG expansion mutations are located in polyGln open reading frames. Additionally, we have developed AAV and small molecule approaches to inhibit RAN translation. We will use these tools and genetic approaches to test our central hypotheses that RAN protein pathology is a common feature shared across polyglutamine encoding CAG·CTG expansion disorders and that inhibiting the PKR pathway will reduce RAN protein levels and mitigate disease. We will address our central hypothesis in three specific aims (1) To test the hypothesis that RAN proteins contribute to spinocerebellar ataxias (SCAs) caused by polyglutamine encoding CAG·CTG repeat expansion mutations. (2) To test the hypothesis that SCA and HD RAN proteins are toxic and PKR inhibition will decrease RAN protein levels and improve cellular phenotypes in HD and SCA3 iPSC derived cells (3) : To test the hypothesis that RAN proteins contribute to HD and SCA3 phenotypes in mice independent of polyGln effects using genetic and pharmacological approaches. Taken together these specific aims will determine the contribution of RAN proteins to HD,SCA3 and CAG·CTG repeat expansion disorders and characterize PKR inhibition as a potential therapeutic approach for this large class of devastating repeat expansion diseases.