Tuberous sclerosis complex (TSC) is a multisystem developmental disorder caused by mutations in the TSC1 or TSC2 genes, whose protein products are negative regulators of mechanistic target of rapamycin complex 1 signaling. Hallmark pathologies of TSC are cortical tubers-regions of dysmorphic, disorganized neurons and glia in the cortex that are linked to epileptogenesis. To determine the developmental origin of tuber cells, we established human cellular models of TSC by CRISPR-Cas9-mediated gene editing of TSC1 or TSC2 in human pluripotent stem cells (hPSCs). Using heterozygous TSC2 hPSCs with a conditional mutation in the functional allele, we show that mosaic biallelic inactivation during neural progenitor expansion is necessary for the formation of dysplastic cells and increased glia production in three-dimensional cortical spheroids. Our findings provide support for the second-hit model of cortical tuber formation and suggest that variable developmental timing of somatic mutations could contribute to the heterogeneity in the neurological presentation of TSC.

中文翻译：

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结节性硬化症的基因工程人类皮质球体模型。

结节性硬化症 (TSC) 是由 TSC1 或 TSC2 基因突变引起的多系统发育障碍，其蛋白质产物是雷帕霉素复合物 1 信号传导机制靶标的负调节剂。TSC 的标志性病变是与癫痫发生有关的皮质块茎区域，即皮质中的畸形、杂乱的神经元和神经胶质细胞。为了确定块茎细胞的发育起源，我们通过 CRISPR-Cas9 介导的人类多能干细胞 (hPSC) 中的 TSC1 或 TSC2 基因编辑建立了人类 TSC 细胞模型。使用在功能等位基因中具有条件突变的杂合 TSC2 hPSC，我们表明在神经祖细胞扩增过程中马赛克双等位基因失活对于发育不良细胞的形成和三维皮质球体中胶质细胞生成的增加是必要的。