Qiu Jia-Jun, Liu Yan-Na, Wei Hao, Zeng Fanyi, Yan Jing-Bin
Shanghai Children's Hospital, Shanghai Institute of Medical Genetics, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
Department of Hiso-Embryology, Genetics and Developmental Biology, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
Front Mol Neurosci. 2023 Jun 15;16:1137123. doi: 10.3389/fnmol.2023.1137123. eCollection 2023.
Down syndrome (DS) is the most common genetic condition that causes intellectual disability in humans. The molecular mechanisms behind the DS phenotype remain unclear. Therefore, in this study, we present new findings on its molecular mechanisms through single-cell RNA sequencing.
Induced pluripotent stem cells (iPSCs) from the patients with DS and the normal control (NC) patients were differentiated into iPSCs-derived neural stem cells (NSCs). Single-cell RNA sequencing was performed to achieve a comprehensive single-cell level differentiation roadmap for DS-iPSCs. Biological experiments were also performed to validate the findings.
The results demonstrated that iPSCs can differentiate into NSCs in both DS and NC samples. Furthermore, 19,422 cells were obtained from iPSC samples (8,500 cells for DS and 10,922 cells for the NC) and 16,506 cells from NSC samples (7,182 cells for DS and 9,324 cells for the NC), which had differentiated from the iPSCs. A cluster of DS-iPSCs, named DS-iPSCs-not differentiated (DSi-PSCs-ND), which had abnormal expression patterns compared with NC-iPSCs, were demonstrated to be unable to differentiate into DS-NSCs. Further analysis of the differentially expressed genes revealed that inhibitor of differentiation family (ID family) members, which exhibited abnormal expression patterns throughout the differentiation process from DS-iPSCs to DS-NSCs, may potentially have contributed to the neural differentiation of DS-iPSCs. Moreover, abnormal differentiation fate was observed in DS-NSCs, which resulted in the increased differentiation of glial cells, such as astrocytes, but decreased differentiation into neuronal cells. Furthermore, functional analysis demonstrated that DS-NSCs and DS-NPCs had disorders in axon and visual system development. The present study provided a new insight into the pathogenesis of DS.
唐氏综合征（DS）是导致人类智力残疾的最常见遗传疾病。DS表型背后的分子机制仍不清楚。因此，在本研究中，我们通过单细胞RNA测序展示了其分子机制的新发现。
将DS患者和正常对照（NC）患者的诱导多能干细胞（iPSC）分化为iPSC来源的神经干细胞（NSC）。进行单细胞RNA测序以获得DS-iPSC全面的单细胞水平分化路线图。还进行了生物学实验以验证这些发现。
结果表明，iPSC在DS和NC样本中均可分化为NSC。此外，从iPSC样本中获得了19422个细胞（DS样本8500个细胞，NC样本10922个细胞），从NSC样本中获得了16506个细胞（DS样本7182个细胞，NC样本9324个细胞），这些细胞均由iPSC分化而来。与NC-iPSC相比，一组表达模式异常的DS-iPSC，命名为DS-iPSC未分化细胞（DSi-PSCs-ND），被证明无法分化为DS-NSC。对差异表达基因的进一步分析表明，分化抑制因子家族（ID家族）成员在从DS-iPSC到DS-NSC的整个分化过程中表现出异常表达模式，可能对DS-iPSC的神经分化有潜在影响。此外，在DS-NSC中观察到异常的分化命运，导致神经胶质细胞（如星形胶质细胞）的分化增加，但神经元细胞的分化减少。此外，功能分析表明，DS-NSC和DS-NPC在轴突和视觉系统发育方面存在障碍。本研究为DS的发病机制提供了新的见解。
