Missense mutations in the gene encoding the microtubule-associated protein TAU (current and approved symbol is MAPT) cause autosomal dominant forms of frontotemporal dementia. Multiple models of frontotemporal dementia based on transgenic expression of human TAU in experimental model organisms, including Drosophila, have been described. These models replicate key features of the human disease but do not faithfully recreate the genetic context of the human disorder. Here we use CRISPR-Cas-mediated gene editing to model frontotemporal dementia caused by the TAU P301L mutation by creating the orthologous mutation, P251L, in the endogenous Drosophila tau gene. Flies heterozygous or homozygous for Tau P251L display age-dependent neurodegeneration, display metabolic defects, and accumulate DNA damage in affected neurons. To understand the molecular events promoting neuronal dysfunction and death in knock-in flies, we performed single-cell RNA sequencing on approximately 130,000 cells from brains of Tau P251L mutant and control flies. We found that expression of disease-associated mutant tau altered gene expression cell autonomously in all neuronal cell types identified. Gene expression was also altered in glial cells, suggestive of non-cell-autonomous regulation. Cell signaling pathways, including glial–neuronal signaling, were broadly dysregulated as were brain region and cell type–specific protein interaction networks and gene regulatory programs. In summary, we present here a genetic model of tauopathy that faithfully recapitulates the genetic context and phenotypic features of the human disease, and use the results of comprehensive single-cell sequencing analysis to outline pathways of neurotoxicity and highlight the potential role of non-cell-autonomous changes in glia.

中文翻译：

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果蝇敲入tau蛋白病模型中介导神经元毒性和神经胶质-神经元信号改变的转录程序

编码微管相关蛋白 TAU（当前和批准的符号是 MAPT）的基因中的错义突变会导致常染色体显性形式的额颞叶痴呆。已经描述了基于实验模型生物（包括果蝇）中人TAU转基因表达的额颞叶痴呆的多种模型。这些模型复制了人类疾病的关键特征，但没有忠实地再现人类疾病的遗传背景。在这里，我们使用 CRISPR-Cas 介导的基因编辑，通过在内源性果蝇 tau基因中创建直系同源突变 P251L，来模拟由 TAU P301L 突变引起的额颞叶痴呆。 Tau P251L 杂合或纯合的果蝇表现出年龄依赖性神经变性、代谢缺陷，并在受影响的神经元中积累 DNA 损伤。为了了解促进敲入果蝇神经元功能障碍和死亡的分子事件，我们对来自 Tau P251L 突变体和对照果蝇大脑的约 130,000 个细胞进行了单细胞 RNA 测序。我们发现，在所有已识别的神经元细胞类型中，与疾病相关的突变tau蛋白的表达会自主改变基因表达细胞。神经胶质细胞中的基因表达也发生了改变，表明存在非细胞自主调节。细胞信号传导途径，包括神经胶质-神经元信号传导，与大脑区域和细胞类型特异性蛋白质相互作用网络和基因调控程序一样广泛失调。总之，我们在此提出了一种 tau 蛋白病的遗传模型，它忠实地概括了人类疾病的遗传背景和表型特征，并利用综合单细胞测序分析的结果来概述神经毒性途径并强调非细胞的潜在作用-神经胶质细胞的自主变化。