Rett syndrome (RTT) is an X-linked, neurodevelopmental disorder caused primarily by mutations in the methyl-CpG-binding protein 2 (MECP2) gene, which encodes a multifunctional epigenetic regulator with known links to a wide spectrum of neuropsychiatric disorders. Although postnatal functions of MeCP2 have been thoroughly investigated, its role in prenatal brain development remains poorly understood. Given the well-established importance of microRNAs (miRNAs) in neurogenesis, we employed isogenic human RTT patient-derived induced pluripotent stem cell (iPSC) and MeCP2 short hairpin RNA knockdown approaches to identify novel MeCP2-regulated miRNAs enriched during early human neuronal development. Focusing on the most dysregulated miRNAs, we found miR-199 and miR-214 to be increased during early brain development and to differentially regulate extracellular signal-regulated kinase (ERK)/mitogen-activated protein kinase and protein kinase B (PKB/AKT) signaling. In parallel, we characterized the effects on human neurogenesis and neuronal differentiation brought about by MeCP2 deficiency using both monolayer and three-dimensional (cerebral organoid) patient-derived and MeCP2-deficient neuronal culture models. Inhibiting miR-199 or miR-214 expression in iPSC-derived neural progenitors deficient in MeCP2 restored AKT and ERK activation, respectively, and ameliorated the observed alterations in neuronal differentiation. Moreover, overexpression of miR-199 or miR-214 in the wild-type mouse embryonic brains was sufficient to disturb neurogenesis and neuronal migration in a similar manner to Mecp2 knockdown. Taken together, our data support a novel miRNA-mediated pathway downstream of MeCP2 that influences neurogenesis via interactions with central molecular hubs linked to autism spectrum disorders.

中文翻译：

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MeCP2调控的miRNA通过对ERK和AKT信号传导的不同作用来控制人类早期的神经发生。

Rett综合征（RTT）是X连锁的神经发育障碍，主要由甲基CpG结合蛋白2（MECP2）基因突变引起，该基因编码一种多功能表观遗传调控因子，与多种神经精神疾病有已知联系。尽管已经对MeCP2的产后功能进行了深入研究，但对其在产前大脑发育中的作用仍知之甚少。鉴于microRNA（miRNA）在神经发生中已确立的重要性，我们采用了等基因人类RTT患者衍生的诱导多能干细胞（iPSC）和MeCP2短发夹RNA敲低方法来鉴定在人类早期神经元发育过程中富集的新型MeCP2调控的miRNA。专注于失调最严重的miRNA，我们发现miR-199和miR-214在早期大脑发育过程中会增加，并差异调节细胞外信号调节激酶（ERK）/丝裂原激活的蛋白激酶和蛋白激酶B（PKB / AKT）信号传导。平行地，我们表征了使用单层和三维（大脑类器官）患者来源的和MeCP2缺乏的神经元培养模型对MeCP2缺乏对人类神经发生和神经元分化的影响。在MeCP2缺陷的iPSC衍生的神经祖细胞中抑制miR-199或miR-214的表达分别恢复了AKT和ERK的激活，并改善了神经元分化中观察到的变化。而且，野生型小鼠胚胎脑中miR-199或miR-214的过表达足以干扰神经发生和神经元迁移，其方式类似于Mecp2敲低。综上所述，我们的数据支持MeCP2下游的新型miRNA介导的途径，该途径通过与与自闭症谱系障碍相关的中心分子枢纽的相互作用影响神经发生。