Hexanucleotide repeat translation in ALS and Frontotemporal Dementia

肌萎缩侧索硬化症(ALS)和额颞叶痴呆(FTD)是常见的神经退行性疾病 进行性的、致命的、没有有效治疗的疾病。最近，最常见的已知 ALS和FTD的病因被确认为基因内含子GGGGCC六核苷酸重复序列的扩张 C9ORF72(C9FTD/ALS)。这种重复通过一种称为重复的过程触发有毒蛋白质的合成 关联的非8月(RAN)转换。这些RAN多肽会杀死神经元，并足以引起 模型系统中的神经退化。我们对Ran翻译如何在C9重复(C9)知之甚少 咆哮)实际上发生了。这项建议的目标是确定C9 RAN和C9 RAN的潜在机制 确定阻断它的方法，作为迈向新治疗开发的第一步。我们的中心假设 C9 RAN利用了一条可以选择性阻断的非规范翻译起始途径。 此外，我们预测，预防C9 RAN将阻止GGGGCC重复引发的神经退行性变。至 为了验证这些假设，我们建立了稳健的、定量的体外和基于细胞的C9 RANT检测方法，AS 以及从患者诱导的多能干细胞、啮齿动物神经元和 果蝇。使用这些工具，我们将定义经历C9 RANT的mRNA物种，识别关键的 基于RNA和蛋白质的因子，允许C9 RANT并测试是否通过调节抑制C9 RANT 在模型系统中，周围的序列或蛋白质因子可以阻止毒性。总而言之，这些研究 应该为我们提供一张C9 RAN是如何发生的工作地图，以及可以采取哪些步骤来防止它。这 项目对我们理解RAN翻译如何有助于 并为c9FTD/ALS和其他疾病的治疗开发提供了一条合理的途径 神经退行性核苷酸重复疾病。

Amyotrophic Lateral Sclerosis (ALS) and Frontotemporal dementia (FTD) are common neurodegenerative disorders that are progressive, fatal, and without effective treatment. Recently, the most common known cause of ALS and FTD was identified as an intronic GGGGCC hexanucleotide repeat expansion in the gene C9orf72 (C9FTD/ALS). This repeat triggers synthesis of toxic proteins via a process known as Repeat Associated Non-AUG (RAN) Translation. These RAN peptides kill neurons and are sufficient to cause neurodegeneration in model systems. We know very little about how RAN translation at C9 repeats (C9 RANT) actually occurs. The objective of this proposal is to determine the mechanisms underlying C9 RAN and to identify methods of blocking it as a first step towards novel therapeutic development. Our central hypothesis is that C9 RAN utilizes a non-canonical translational initiation pathway that can be selectively blocked. Moreover, we predict that preventing C9 RAN will stop neurodegeneration elicited by GGGGCC repeats. To test these hypotheses, we developed robust and quantitative in vitro and cell based assays of C9 RANT, as well as a collection of models derived from patient induced pluripotent stem cells, rodent neurons, and Drosophila. Using these tools, we will define the mRNA species that undergo C9 RANT, identify the critical RNA and protein based factors that allow for C9 RANT and test whether suppressing C9 RANT by modulating the surrounding sequence or protein factors can block toxicity in model systems. Together, these studies should provide us with a working map of how C9 RAN occurs and what steps can be taken to prevent it. This project has broad reaching implications both for our understanding of how RAN translation contributes to disease as well as providing a logical path towards therapeutic development in C9FTD/ALS and other neurodegenerative nucleotide repeat disorders.