Dipeptide repeat proteins are a major pathogenic feature of C9orf72 amyotrophic lateral sclerosis (C9ALS)/frontotemporal dementia (FTD) pathology, but their physiological impact has yet to be fully determined. Here we generated C9orf72 dipeptide repeat knock-in mouse models characterized by expression of 400 codon-optimized polyGR or polyPR repeats, and heterozygous C9orf72 reduction. (GR)400 and (PR)400 knock-in mice recapitulate key features of C9ALS/FTD, including cortical neuronal hyperexcitability, age-dependent spinal motor neuron loss and progressive motor dysfunction. Quantitative proteomics revealed an increase in extracellular matrix (ECM) proteins in (GR)400 and (PR)400 spinal cord, with the collagen COL6A1 the most increased protein. TGF-β1 was one of the top predicted regulators of this ECM signature and polyGR expression in human induced pluripotent stem cell neurons was sufficient to induce TGF-β1 followed by COL6A1. Knockdown of TGF-β1 or COL6A1 orthologues in polyGR model Drosophila exacerbated neurodegeneration, while expression of TGF-β1 or COL6A1 in induced pluripotent stem cell-derived motor neurons of patients with C9ALS/FTD protected against glutamate-induced cell death. Altogether, our findings reveal a neuroprotective and conserved ECM signature in C9ALS/FTD.

二肽重复蛋白是C9orf72肌萎缩侧索硬化症 (C9ALS)/额颞叶痴呆 (FTD) 病理学的主要致病特征，但其生理影响尚未完全确定。在这里，我们生成了C9orf72二肽重复敲入小鼠模型，其特征是表达 400 个密码子优化的 PolyGR 或 PolyPR 重复，以及杂合C9orf72减少。(GR)400 和 (PR)400 敲入小鼠概括了 C9ALS/FTD 的关键特征，包括皮质神经元过度兴奋、年龄依赖性脊髓运动神经元丧失和进行性运动功能障碍。定量蛋白质组学显示 (GR)400 和 (PR)400 脊髓中细胞外基质 (ECM) 蛋白增加，其中胶原蛋白 COL6A1 增加最多。TGF-β1 是该 ECM 特征的最高预测调节因子之一，并且人类诱导多能干细胞神经元中的 polyGR 表达足以诱导 TGF-β1，然后诱导 COL6A1。在polyGR模型中敲低TGF-β1或COL6A1直向同源物会加剧神经变性，而在C9ALS/FTD患者的诱导多能干细胞衍生的运动神经元中表达TGF-β1或COL6A1可防止谷氨酸诱导的细胞死亡。总而言之，我们的研究结果揭示了 C9ALS/FTD 中具有神经保护作用且保守的 ECM 特征。