Examining cross-species suppression of neurodegeneration by loss of a conserved RNA binding protein in models of ALS and FTD

额颞叶痴呆（FTD）和肌萎缩侧索硬化症（ALS）的病因机制是 定义不明确，但多个基因突变可导致FTD，ALS或混合临床综合征。这 表明共同的分子途径是疾病发病机制的基础。基于表型的遗传学研究 在模式生物中是鉴定这些致病机制和潜在的 治疗目标在这里，我们集中在一个保守的RNA结合蛋白，它抑制病理在一个特定的细胞。 C. ALS的遗传模型优雅我们建议开始分析抑制机制， 在两种C.线虫和老鼠 从历史上看，FTD/ALS领域的工作依赖于错误或过度表达疾病蛋白的动物模型。 然而，疾病蛋白质在患者中并不过度表达，野生型蛋白质的过度表达通常是 因此，从错误/过度表达的人为影响中解开疾病机制， 挑战性相反，我们主要依赖于敲入模型，通过直接编辑内源基因来创建， 插入患者氨基酸变化。在我们的C。在线虫sod-1G 85 R敲入模型中，我们观察到 应激诱导的胆碱能和多巴胺能神经元变性，但多巴胺能或 肾上腺素能神经元。使用类似的方法来开发小鼠基因敲入小鼠模型， Sod 1G 85 R，表现出进行性运动神经元变性。我们进行了第一次基因抑制 使用敲入动物模型进行筛选，并鉴定了一种RNA结合蛋白，其功能丧失 在敲入sod-1G 85 RC中抑制多巴胺能和胆碱能神经变性。优雅 有趣的是，这种RNA结合蛋白的脊椎动物直系同源物在轴突的RNA/蛋白颗粒中被发现。 过程，沿着HNRNPA 1，FUS和其他突变导致FTD/ALS的蛋白质， 鉴定为C9 orf 72相关二肽重复诱导毒性的抑制剂。 了解这种RNA结合蛋白的丢失如何抑制神经变性可能会为以下方面提供见解： 为什么SOD 1、HNRNPA 1、FUS或其他蛋白质突变会导致FTD/ALS。在我们的第一个目标中，我们计划 确定C中的抑制机制。elegans和检查这种抑制剂的能力， 其他FTD/ALS模型（C9 orf 72、HNRNPA 1、FUS和TDP 43）中的变性。此外，重要的是 确定这种RNA结合蛋白的缺失是否也能抑制脊椎动物模型的退化。在 第二个目的，我们评估了小鼠SOD 1G 85 R基因敲入模型中抑制的保守性。综合起来， 这些目标将提供对致病机制的深入了解，可能将SOD 1相关ALS与FTD/ALS联系起来 由其他RNA结合蛋白（如FUS）突变引起，并将有助于确定未来的深入研究 在脊椎动物模型中，有必要开发靶向RNA结合蛋白的治疗干预措施 由这个抑制基因编码

Etiological mechanisms for Frontotemporal Dementia (FTD) and Amyotrophic Lateral Sclerosis (ALS) are poorly defined, but mutations in multiple genes can cause FTD, ALS, or a mixed clinical syndrome. This suggests that common molecular pathways underlie disease pathogenesis. Phenotype-based genetic studies in model organisms are a powerful strategy for identifying these pathogenic mechanisms and potential therapeutic targets. Here, we focus on a conserved RNA-binding protein, which suppresses pathology in a genetic model for ALS in C. elegans. We propose to initiate analysis of the mechanism of suppression and to test for beneficial effects in additional FTD/ALS models in both C. elegans and mice. Historically, work in the FTD/ALS field has relied on animal models that mis- or over-express disease proteins. However, disease proteins are not over-expressed in patients, over-expression of wild-type protein is often toxic, and disentangling disease mechanisms from artificial effects of mis-/over-expression is therefore challenging. Instead, we primarily rely on knock-in models, created by directly editing the endogenous genes to insert patient amino acid changes. In our C. elegans knock-in model for sod-1G85R, we observe stress-induced degeneration of cholinergic and glutamatergic neurons, but not loss of dopaminergic or serotonergic neurons. A similar approach was used to develop the mouse knock-in mouse model for Sod1G85R, which exhibits progressive motor neuron degeneration. We undertook the first genetic suppressor screen using a knock-in animal model and identified an RNA-binding protein whose loss of function suppresses both glutamatergic and cholinergic neurodegeneration in knock-in sod-1G85R C. elegans. Intriguingly, a vertebrate ortholog of this RNA-binding protein is found in RNA/protein granules in axonal processes, along with HNRNPA1, FUS, and other proteins whose mutation causes FTD/ALS, and was identified as a suppressor of C9orf72-associated dipeptide repeat-induced toxicity. Understanding how loss of this RNA binding protein suppresses neurodegeneration may provide insights into why mutation of SOD1, HNRNPA1, FUS, or other proteins leads to FTD/ALS. In our first aim, we plan to identify the mechanism of suppression in C. elegans and examine the ability of this suppressor to decrease degeneration in other models of FTD/ALS (C9orf72, HNRNPA1, FUS, and TDP43). Further, it is important to determine whether loss of this RNA binding protein can also suppress degeneration in vertebrate models. In the second aim, we assess conservation of suppression in the murine SOD1G85R knock-in model. Combined, these aims will provide insight into pathogenic mechanisms, may link SOD1-associated ALS to FTD/ALS caused by mutation of other RNA-binding proteins (e.g. FUS), and will help determine if future in-depth studies in vertebrate models are warranted to develop therapeutic interventions that target the RNA-binding protein encoded by this suppressor gene.