多体系萎缩(MSA)是一种致命的神经退行性疾病。类似于帕金森病(PD),MSA是一种α-突触核蛋白病,其病理标志包括少突胶质细胞中含有α-突触核蛋白(SNCA)的神经胶质细胞质内含物(GCI)。我们先前在MSA中发现了髓鞘相关少突胶质细胞碱性蛋白(MOBP)和亨廷顿蛋白相互作用蛋白1(HIP1)DNA甲基化状态的一致变化。我们假设,如果这些基因座的差异DNA甲基化与MSA在机械上相关,它应该对基因调控产生下游影响。
我们研究了来自MSA和健康对照的小脑白质中MOBP和HIP1DNA甲基化和mRNA水平之间的关系。此外,我们用蛋白质印迹分析了蛋白质表达,免疫组织化学和邻近连接测定。
我们发现MSA中MOBPmRNA水平降低与DNA甲基化增加显著相关。对于HIP1,我们发现与健康对照相比,MSA中DNA甲基化和基因表达水平之间存在明显的关系。表明该基因座可能在MSA中进行表观遗传重塑。尽管在MSA病例和对照组之间,小脑白质中MOBP和HIP1的可溶性蛋白水平没有显着差异,我们发现MSA和其他神经退行性疾病之间存在显著差异,包括PD和亨廷顿病.我们还发现MOBP和HIP1错误定位到MSA中的GCI中,他们似乎与SNCA互动。
这项研究支持DNA甲基化在MSA中MOBPmRNA下调中的作用。最重要的是,MOBP和HIP1作为GCI的新成分的鉴定强调了这两个基因座与MSA发病机理的相关性。
Multiple system atrophy (MSA) is a fatal neurodegenerative disease. Similar to Parkinson\'s disease (PD), MSA is an α-synucleinopathy, and its pathological hallmark consists of glial cytoplasmic inclusions (GCIs) containing α-synuclein (SNCA) in oligodendrocytes. We previously identified consistent changes in myelin-associated oligodendrocyte basic protein (MOBP) and huntingtin interacting protein 1 (HIP1) DNA methylation status in MSA. We hypothesized that if differential DNA methylation at these loci is mechanistically relevant for MSA, it should have downstream consequences on gene regulation.
We investigated the relationship between MOBP and HIP1 DNA methylation and mRNA levels in cerebellar white matter from MSA and healthy controls. Additionally, we analysed protein expression using western blotting, immunohistochemistry and proximity ligation assays.
We found decreased MOBP mRNA levels significantly correlated with increased DNA methylation in MSA. For HIP1, we found a distinct relationship between DNA methylation and gene expression levels in MSA compared to healthy controls, suggesting this locus may be subjected to epigenetic remodelling in MSA. Although soluble protein levels for MOBP and HIP1 in cerebellar white matter were not significantly different between MSA cases and controls, we found striking differences between MSA and other neurodegenerative diseases, including PD and Huntington\'s disease. We also found that MOBP and HIP1 are mislocalized into the GCIs in MSA, where they appear to interact with SNCA.
This study supports a role for DNA methylation in downregulation of MOBP mRNA in MSA. Most importantly, the identification of MOBP and HIP1 as new constituents of GCIs emphasizes the relevance of these two loci to the pathogenesis of MSA.