The pathogenic relationship between neuronal activity and C9orf72-linked neurodegeneration

项目摘要 9号染色体开放阅读框72（C9 orf 72）上的核苷酸重复扩增（NRE）突变已被证实是一种新的突变。 被确定为与额颞叶痴呆（FTD）和肌萎缩侧索硬化症（ALS）相关的最常见的基因突变。 硬化症（ALS）。很明显，这两种疾病存在于一系列神经系统和 基于在患者死后组织中鉴定的重叠病理学特征的神经肌肉疾病， 然而神经发病机制的原因尚不清楚。依赖性高兴奋性和/或低兴奋性 是ALS的一个充分描述的特征，目前正在FTD/ALS患者中报告， 多能干细胞（iPSC）是携带C9 orf 72 NRE突变的多能干细胞。此外，异常的神经元活动 随着年龄的增长而增加，并且可以促进动物模型中的加速老化。虽然神经特异性 C9 orf 72蛋白的功能丧失的贡献没有得到很好的描述，两个C9 orf 72 NRE功能获得 机制，来自NRE双向转录的RNA毒性和/或二肽重复序列（DPR）毒性 来自NRE的非AUG依赖性翻译，已被证明有助于神经毒性机制。 我们最近发现了异常神经元活动和DPR毒性增加之间的潜在联系， 增加的兴奋性毒性应激或重复的神经元活化可驱动DPR产生。但进一步 研究对于理解这些体外观察结果并确定这些观察结果是否有助于 体内C9 orf 72 NRE相关疾病发病机制。因此，在本研究提案中，我们假设， 异常活性增加神经生理应激，其可以改变C9 orf 72 NRE相关神经发病机制 从而增加C9 orf 72 NRE细菌人工染色体（BAC）疾病的病理负担 模型，目前缺乏明显或稳健的FTD或ALS表型。此外，我们假设， 活性将改变时空功能获得毒性。为了验证这些假设，我们将使用一组 同时利用C9 orf 72 NRE人iPSC和体内模型来测试 异常神经元活动与C9 orf 72 NRE时空动力学因果关系 RNA和DPR使用新的患者来源的神经元模型，然后验证这些发现在体内。最后， 我们预计，这项工作将为理解时空因果关系奠定重要基础。 异常神经元活动引起的神经生理应激与C9-RNE相关的 在体外和体内的发病机制，以及揭示新的治疗干预机会，以治疗 与C9-NRE突变相关的神经再生障碍。

Project Summary The nucleotide repeat expansion (NRE) mutation on chromosome 9 open reading frame 72 (C9orf72) has been identified as the most common genetic mutation link to frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS). It has become clear that these two diseases exist in a spectrum of neurological and neuromuscular disorders based on overlapping pathological features identified in patients post-mortem tissue, yet the mechanistic cause for neuropathogenesis is unclear. Age-dependent hyper- and/or hypo-excitability has been a well-described feature of ALS and is now being reported in FTD/ALS patients and patient-derived induced pluripotent stem cells (iPSCs) that carry the C9orf72 NRE mutation. Moreover, aberrant neuronal activity increases with age and can contribute to accelerated aging in animal models. Although the neurospecific contribution for loss-of-function of the C9orf72 protein is not well described, two C9orf72 NRE gain-of-function mechanisms, RNA toxicity from the bidirectional transcription of the NRE and/or dipeptide repeat (DPR) toxicity from the non-AUG-dependent translation of the NRE, have been shown to contribute to neurotoxic mechanisms. We recently identified a potential link between aberrant neuronal activity and increased DPR toxicity, where increased excitotoxic stress or repetitive neuronal activation can drive DPR production. However, further investigation is crucial to understand these in vitro observations and to determine if these may contribute to C9orf72 NRE-linked disease pathogenesis in vivo. Therefore, in this research proposal we hypothesize that abnormal activity increase neurophysiological stress that can modify C9orf72 NRE-linked neuropathogenesis and thereby increase the pathological burden in C9orf72 NRE bacterial artificial chromosome (BAC) disease models, which currently lack overt or robust FTD or ALS phenotypes. Additionally, we postulate that aberrant activity will alter the spatiotemporal gain-of-function toxicity. To test these hypotheses, we will utilize a battery of biochemical to cellular longitudinal assays while utilizing C9orf72 NRE human iPSC and in vivo models to test the causal relationship among aberrant neuronal activity and spatiotemporal dynamics of C9orf72 NRE derived RNA and DPRs using novel patient derived neuronal models and then validate these finds in vivo. Ultimately, we anticipate that this work will establish a crucial foundation for understanding the spatiotemporal causal relationship between neurophysiological stress caused by aberrant neuronal activity and C9-RNE-linked pathogenesis in vitro and in vivo, as well as reveal new therapeutic intervention opportunities to treat neurogenerative disorders linked to the C9-NRE mutation.