Appleby-Mallinder C, Schaber E, Kirby J, Shaw P J, Cooper-Knock J, Heath P R, Highley J R
Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, Sheffield, United Kingdom.
Department of Cellular Pathology, Hull Royal Infirmary, Hull, United Kingdom.
Neuropathol Appl Neurobiol. 2021 Feb;47(1):61-72. doi: 10.1111/nan.12625. Epub 2020 May 19.
Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by motor neurone (MN) degeneration and death. ALS can be sporadic (sALS) or familial, with a number of associated gene mutations, including C9orf72 (C9ALS). DNA methylation is an epigenetic mechanism whereby a methyl group is attached to a cytosine (5mC), resulting in gene expression repression. 5mC can be further oxidized to 5-hydroxymethylcytosine (5hmC). DNA methylation has been studied in other neurodegenerative diseases, but little work has been conducted in ALS.
To assess differences in DNA methylation in individuals with ALS and the relationship between DNA methylation and TDP43 pathology.
Post mortem tissue from controls, sALS cases and C9ALS cases were assessed by immunohistochemistry for 5mC and 5hmC in spinal cord, motor cortex and prefrontal cortex. LMNs were extracted from a subset of cases using laser capture microdissection. DNA from these underwent analysis using the MethylationEPIC array to determine which molecular processes were most affected.
There were higher levels of 5mC and 5hmC in sALS and C9ALS in the residual lower motor neurones (LMNs) of the spinal cord. Importantly, in LMNs with TDP43 pathology there was less nuclear 5mC and 5hmC compared to the majority of residual LMNs that lacked TDP43 pathology. Enrichment analysis of the array data suggested RNA metabolism was particularly affected.
DNA methylation is a contributory factor in ALS LMN pathology. This is not so for glia or neocortical neurones.
肌萎缩侧索硬化症（ALS）是一种致命的神经退行性疾病，其特征为运动神经元（MN）变性和死亡。ALS 可分为散发性（sALS）或家族性，与多种相关基因突变有关，包括 C9orf72（C9ALS）。DNA 甲基化是一种表观遗传机制，通过该机制甲基基团附着于胞嘧啶（5mC），导致基因表达受抑制。5mC 可进一步氧化为 5 - 羟甲基胞嘧啶（5hmC）。DNA 甲基化已在其他神经退行性疾病中得到研究，但在 ALS 方面的研究较少。
评估 ALS 患者的 DNA 甲基化差异以及 DNA 甲基化与 TDP43 病理学之间的关系。
通过免疫组织化学对对照、sALS 病例和 C9ALS 病例的死后组织进行脊髓、运动皮层和前额叶皮层中 5mC 和 5hmC 的评估。使用激光捕获显微切割从部分病例中提取下运动神经元（LMN）。对这些样本的 DNA 使用甲基化 EPIC 阵列进行分析，以确定哪些分子过程受影响最大。
在脊髓残留的下运动神经元（LMN）中，sALS 和 C9ALS 患者的 5mC 和 5hmC 水平较高。重要的是，与大多数缺乏 TDP43 病理学特征的残留 LMN 相比，具有 TDP43 病理学特征的 LMN 中核内 5mC 和 5hmC 较少。阵列数据的富集分析表明 RNA 代谢受到特别影响。
DNA 甲基化是 ALS 下运动神经元病理学的一个促成因素。对于神经胶质细胞或新皮质神经元并非如此。
