Single copy/knock-in models of ALS SOD1 in C. elegans suggest loss and gain of function have different contributions to cholinergic and glutamatergic neurodegeneration
Single copy/knock-in models of ALS SOD1 in C. elegans suggest loss and gain of function have different contributions to cholinergic and glutamatergic neurodegeneration
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DOI：
10.1371/journal.pgen.1007682
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发表时间：
2018-10-01
期刊：
影响因子：
4.5
通讯作者：
Hart, Anne C.
中科院分区：
文献类型：
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作者：
Baskoylu, Saba N.;Yersak, Jill;Hart, Anne C.
铜/锌超氧化物歧化酶 1 (SOD1) 的突变会导致肌萎缩侧索硬化症 (ALS)，这是一种神经退行性疾病，对谷氨酸能和胆碱能运动神经元产生不成比例的影响。先前对 SOD1 过表达模型的研究支持 SOD1 毒性功能获得在 ALS 发病机制中的作用。然而，SOD1 功能丧失对 ALS 的影响无法在过表达模型中直接检查。此外，过度表达可能掩盖 SOD1 功能丧失在不同神经元群体退化中的作用。在这里，我们报告了通过转座子或 CRISPR/Cas9 介导的内源 sod-1 基因的基因组编辑产生的第一个单拷贝 ALS 敲入模型。将 ALS 患者氨基酸变化 A4V、H71Y、L84V、G85R 或 G93A 引入秀丽隐杆线虫 sod-1 基因中，产生单拷贝/敲入 ALS SOD1 模型。这些与先前报道的多种测定中的过度表达模型不同。在单拷贝/敲入模型中，我们观察到 sod-1 ALS 等位基因对谷氨酸能和胆碱能神经变性的不同影响。 A4V、H71Y、G85R 和 G93A 动物表现出 SOD1 蛋白积累增加和氧化应激诱导的变性，与胆碱能运动神经元功能的毒性增强一致。相比之下，H71Y、L84V 和 G85R 由于氧化应激后 sod-1 功能丧失而导致谷氨酸能神经元变性。然而，多巴胺能和血清素能神经元群在单拷贝 ALS 模型中幸存下来，这表明以前在无脊椎动物 ALS SOD1 模型中未报道过神经元亚型特异性。综合起来，这些结果表明，敲入模型可以重现 ALS 的神经递质类型特异性，并且 SOD1 的丧失和毒性功能的获得对不同神经元群体的 ALS 发病机制有不同的贡献。
Mutations in Cu/Zn superoxide dismutase 1 (SOD1) lead to Amyotrophic Lateral Sclerosis (ALS), a neurodegenerative disease that disproportionately affects glutamatergic and cholinergic motor neurons. Previous work with SOD1 overexpression models supports a role for SOD1 toxic gain of function in ALS pathogenesis. However, the impact of SOD1 loss of function in ALS cannot be directly examined in overexpression models. In addition, overexpression may obscure the contribution of SOD1 loss of function in the degeneration of different neuronal populations. Here, we report the first single-copy, ALS knock-in models in C. elegans generated by transposon-or CRISPR/Cas9-mediated genome editing of the endogenous sod-1 gene. Introduction of ALS patient amino acid changes A4V, H71Y, L84V, G85R or G93A into the C. elegans sod-1 gene yielded single-copy/knock-in ALS SOD1 models. These differ from previously reported overexpression models in multiple assays. In single-copy/knock-in models, we observed differential impact of sod-1 ALS alleles on glutamatergic and cholinergic neurodegeneration. A4V, H71Y, G85R, and G93A animals showed increased SOD1 protein accumulation and oxidative stress induced degeneration, consistent with a toxic gain of function in cholinergic motor neurons. By contrast, H71Y, L84V, and G85R lead to glutamatergic neuron degeneration due to sod-1 loss of function after oxidative stress. However, dopaminergic and serotonergic neuronal populations were spared in single-copy ALS models, suggesting a neuronal-subtype specificity previously not reported in invertebrate ALS SOD1 models. Combined, these results suggest that knock-in models may reproduce the neurotransmitter-type specificity of ALS and that both SOD1 loss and gain of toxic function differentially contribute to ALS pathogenesis in different neuronal populations.