Single-nucleus sequencing reveals enriched expression of genetic risk factors in Extratelencephalic Neurons sensitive to degeneration in ALS. Single-nucleus sequencing reveals enriched expression of genetic risk factors in Extratelencephalic Neurons sensitive to degeneration in ALS

Amyotrophic Lateral Sclerosis (ALS) is a fatal neurodegenerative disorder characterised by a progressive loss of motor function. The eponymous spinal sclerosis observed at autopsy is the result of the degeneration of extratelencephalic neurons, Betz cells (ETNs, Cortico-Spinal Motor Neuron). It remains unclear why this neuronal subtype is selectively affected. To understand the unique molecular properties that sensitise these cells to ALS, we performed RNA sequencing of 79,169 single nuclei from cortices of patients and controls. In unaffected individuals, we found that expression of ALS risk genes was significantly enriched in THY1+-ETNs and not in other cell types. In patients, these genetic risk factors, as well as genes involved in protein homeostasis and stress responses, were significantly induced in a wide collection of ETNs, but not in neurons with more superficial identities. Examination of oligodendroglial and microglial nuclei revealed patient-specific changes that were at least in part a response to alterations in neurons: downregulation of myelinating genes in oligodendrocytes and upregulation of a reactive state connected to endo-lysosomal pathways in microglia. Our findings suggest that the selective vulnerability of extratelencephalic neurons is partly connected to their intrinsic molecular properties sensitising them to genetics and mechanisms of degeneration. Overall design: Pooled "villages" of lower induced Motor Neurons differentiated from human stem-cells (ALS or control) were analyzed using scRNAseq >>>Raw data are not available due to patient privacy concerns<<<

肌萎缩侧索硬化症（Amyotrophic Lateral Sclerosis, ALS）是一种致命的神经退行性疾病，以运动功能进行性丧失为核心特征。尸检中观察到的同名脊髓硬化，是脑外神经元（Betz细胞，即皮质脊髓运动神经元，ETNs）变性的病理结果。目前学界仍未明确该神经元亚型为何会发生选择性损伤。为阐明使这些细胞对ALS易感的独特分子特性，我们对来自ALS患者与健康对照者的皮层组织，完成了79169个单细胞核的RNA测序。在未受疾病累及的个体中，ALS风险基因的表达显著富集于THY1阳性脑外神经元（THY1+-ETNs）中，而非其他细胞类型。在ALS患者体内，这类遗传风险因子以及参与蛋白质稳态与应激反应的基因，在大量ETNs中均出现显著上调，但在具有更浅层表型的神经元中无此类变化。对少突胶质细胞核与小胶质细胞核的分析显示，患者特异性的分子变化至少部分源于对神经元改变的响应：少突胶质细胞内髓鞘形成相关基因的表达下调，小胶质细胞内与内溶酶体通路（endo-lysosomal pathways）相关的反应性状态相关基因的表达上调。本研究结果表明，脑外神经元的选择性易感性，部分与其内在的分子特性相关——这些特性使它们对遗传风险因素与变性机制更为敏感。整体实验设计：将源自人类干细胞（ALS患者或对照个体）诱导分化的下运动神经元的集合“群落”进行混合，采用单细胞RNA测序（scRNAseq）进行分析>>>由于患者隐私保护需求，原始数据暂不对外公开<<<