Molecular Phenotyping of Cortical Cell Types in ALS Related Neurodegeneration

摘要 脑干脊髓“下”运动神经元和“上”运动神经元的联合变性 大脑皮层运动神经元(UMN)是ALS的重要标志。几乎所有的ALS病例都是 最终是致命的，这种疾病的快速发展使其特别可怕，超过80%的 患者在确诊后五年内死亡。肌萎缩侧索硬化症没有治愈方法，唯一可用的治疗方法是缓慢的 疾病进展只有几个月。因此，迫切需要更有效和更具体的 可以阻止甚至逆转神经退化的疗法。这种疗法的创新只会产生于 更好地理解病理过程背后的分子机制。大多数基因都与 肌萎缩侧索硬化症普遍表达，但只有特定的细胞群退化。了解为什么某些 细胞是唯一脆弱的，在疾病期间被失调的映射细胞类型特定的通路是 开发创新疗法的关键里程碑。这给脊椎带来了相当大的挑战 脊髓投射上运动神经元(UMN)，因为它们很难与其他锥体细胞区分 类型，因此在临床前研究中常常被忽视。正因为如此，他们选择的基础 对致病突变的脆弱性仍然是一个谜。 这项拟议的研究旨在通过在最近的工作基础上发现两个高度相似的 然而，UMN所在的运动皮质5b层的投射神经元亚群在分子上是不同的。 这些人群对脑桥有重叠的投射，但对脊髓或 丘脑。在ALS的临床前模型中检查这些细胞发现，皮质脊髓投射神经元 (CSTN)容易退化，而仅皮质桥脑(CPN)种群不退化。 CSTN的选择性脆弱性可能是由于线粒体功能失调所致 与氧化磷酸化和有丝分裂相关的基因显著上调 疾病的症状阶段。这笔赠款的目标1将采用综合多组学方法来解决 CSTN和CPN之间线粒体特性的差异是否会导致对 在疾病进展过程中使用一种新的基于病毒的策略来分离细胞类型特定的线粒体 在两个临床前ALS模型中，SOD1G93A和FUSP525L。目标2侧重于描述细胞角色的特征 已确定的候选基因富含CSTN，显示定位于线粒体，并已被 与肌萎缩侧索硬化症和其他神经退行性疾病的临床病例直接相关。要提高翻译能力， 这项工作的意义，Aim 3将利用CSTN和CPN的新标记进行详细的解剖 肌萎缩侧索硬化症患者死后组织的细胞类型特异性核转录图谱分析 通过荧光激活的核分类(FANS)从死后患者组织中分离出。由此产生的结果 研究将产生肌萎缩侧索硬化症中UMNS选择性易损性的新机制。

SUMMARY The combined degeneration of both “lower” motor neurons in the brainstem and spinal cord and “upper” motor neurons (UMNs) in the cerebral cortex is an important hallmark of ALS. 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 treatments slow 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. Most genes linked to ALS are ubiquitously expressed yet only specific populations of cells degenerate. Understanding why certain cells are uniquely vulnerable and mapping cell type specific pathways that are dysregulated during disease are crucial milestones for developing innovative therapies. This has posed a considerable challenge for the spinal cord-projecting upper motor neurons (UMNs) since they are difficult to distinguish from other pyramidal cell types and are therefore often overlooked in preclinical studies. Because of this, the basis for their selective vulnerability to disease-causing mutations has remained a mystery. The proposed study aims to overcome this by building on recent work that identified two highly similar yet molecularly distinct subpopulations of projection neurons in layer 5b of motor cortex, where UMNs reside. These populations have overlapping projections to pons, but non-overlapping projections to the spinal cord or thalamus. Examining these cells in preclinical models of ALS revealed that the corticospinal projecting neurons (CSTNs) were vulnerable to degeneration, while the corticopontine-only population (CPN) did not degenerate. The selective vulnerability of the CSTNs was likely due to dysregulation of mitochondrial function since a dramatic upregulation of genes related to oxidative phosphorylation and mitophagy was observed at symptomatic stages of disease. Aim 1 of this grant will employ an integrative multi-omics approach to address whether differences in the properties of mitochondria between CSTNs and CPNs drive differential responses to disease using a novel, viral-based strategy to isolate cell type specific mitochondria during disease progression in two preclinical ALS models, SOD1G93A and FUSP525L. Aim 2 focuses on characterizing the cellular role of identified candidate genes that are enriched in CSTNs, shown to localize to mitochondria, and have been directly linked to clinical cases of ALS and other neurodegenerative disorders. To increase the translational significance of this work, Aim 3 will leverage novel markers for CSTNs and CPNs for a detailed anatomical analysis of postmortem tissue from ALS patients perform transcriptional profiling on cell type specific nuclei isolated by fluorescence activated nuclear sorting (FANS) from postmortem patient tissue. Results from this study will yield novel mechanisms underlying selective vulnerability of UMNs in ALS.