Molecular phenotyping of cortical cell types in multiple rodent models of ALS

 描述（由申请人提供）：目前超过30，000名美国人患有肌萎缩性侧索硬化症（ALS），其特征在于由于控制肌肉的大脑和脊髓中的神经细胞变性而导致的进行性瘫痪。几乎所有的ALS病例最终都是致命的，疾病的快速进展使其特别可怕，超过80%的患者在诊断后五年内死亡。ALS没有治愈的方法，唯一可用的治疗方法只能减缓疾病进展几个月。因此，非常需要能够阻止甚至逆转神经变性的更有效和特异性的疗法。只有更好地理解病理过程背后的分子机制，才能对此类疗法进行创新。 这项研究旨在确定大脑皮层特定细胞群中疾病进展过程中失调的分子和途径，包括脆弱的“上”运动神经元（UMN）。由于皮层结构的复杂性阻碍了区分细胞群的能力，以前从未进行过这样的分析。遗传学研究已经将许多基因与ALS病理学联系起来，包括SOD1，TDP43和FUS，但所有这些基因都在全身许多细胞类型中广泛表达，而ALS仅影响CNS中的某些细胞。该项目将利用新的翻译核糖体亲和纯化（TRAP）方法，通过允许检查从遗传定义的细胞类型的蛋白质翻译来克服这些限制。将在四种皮质细胞类型（两个脆弱UMN群体、非脆弱神经元群体和星形胶质细胞）中携带TRAP转基因的工程小鼠（bacTRAP小鼠）与三种ALS小鼠模型杂交，所述ALS小鼠模型利用SOD1（G93A）、TDP43（M337V）和FUS（P525L）基因中的疾病相关突变。这些模型概括了在人类患者中观察到的神经变性，并将能够全面评估ALS病理过程中细胞类型特异性分子变化。 将通过分析每个模型中三个时间点（早期、症状前和晚期）的TRAP翻译谱来确定疾病进展期间基因表达的变化。虽然这是一个 在临床前基础研究项目中，将集中精力确定具有最强和最直接临床影响的候选基因。将特别强调发生在早期和症状前阶段的变化，因为早期干预可能会增加成功率。这些研究旨在通过在多种模型中探测脆弱细胞中特异性改变的基因来提高动物模型治疗的成功率。拟议研究的结果将为该领域提供新基因和信号通路的宝贵资源，以作为治疗ALS的更特异和创新疗法的候选靶点。

 DESCRIPTION (provided by applicant): Over 30,000 Americans currently suffer from amyotrophic lateral sclerosis (ALS) which is characterized by progressive paralysis due to the degeneration of nerve cells in the brain and spinal cord that control muscles. Almost all cases of ALS are eventually fatal and the rapid progression of the disease makes it particularly terrible, with over 80% of patients dying within five years of diagnosis. No cure exists for ALS and the only available treatment slows disease progression by merely a few months. Therefore a great need exists for more effective and specific therapies that can stop or even reverse neurodegeneration. Innovation for such therapies will only arise from a better understanding of the molecular mechanisms underlying the pathological process. The proposed study aims to identify molecules and pathways dysregulated during disease progression in specific cell populations in the cerebral cortex, including the vulnerable "upper" motor neurons (UMNs). Such an analysis has never been done before due to the complexity of cortical architecture hampering the ability to distinguish between cell populations. Genetic studies have linked a number of genes to ALS pathology, including SOD1, TDP43, and FUS, yet all of these genes are widely expressed in many cell types throughout the body while ALS afflicts only certain cells in the CNS. This project will utilize the novel translating ribosome affinity purification (TRAP) methodology to overcome these limitations by allowing for the examination of protein translation from genetically defined cell types. Engineered mice harboring the TRAP transgene (bacTRAP mice) in four cortical cell types (two populations of vulnerable UMNs, a non-vulnerable neuronal population, and astrocytes) will be crossed to three mouse models of ALS that utilize disease-linked mutations in the SOD1 (G93A), TDP43 (M337V), and FUS (P525L) genes. These models recapitulate the neurodegeneration seen in human patients and will enable a comprehensive assessment of cell-type specific molecular changes during ALS pathology. Changes in gene expression during disease progression will be determined by analyzing TRAP translational profiles at three time points (early, pre-symptomatic, and late) within each model. While this is a pre-clinical basic research project, efforts will be focused on identifying candidate genes that wil have the strongest and most immediate clinical impact. Particular emphasis will be placed on changes that occur at early and pre-symptomatic stages since earlier intervention will likely have an increased rate of success. These studies aim to improve upon the success rate of therapies arising from animal models by probing genes altered specifically in vulnerable cells across multiple models. Results from the proposed study will provide the field with a valuable resource of novel genes and signaling pathways to serve as candidate targets for more specific and innovative therapeutics to treat ALS.