Identifying developmental trajectories characterized in the neuroepithelial stem cell to radial glia transition using single-cell transcriptomics

项目摘要/摘要 人类大脑皮层由数十亿个细胞组成，这些细胞主要是在发育过程中产生的 各阶段。在神经发育过程中，神经上皮细胞产生放射状胶质细胞，这是典型的神经。 干细胞。放射状胶质细胞然后不对称地分裂为运输放大中间前体细胞，这 分化为兴奋性神经元。这些神经发生的步骤已经在 文学。然而，致力于理解分子同一性的研究很少。 神经上皮干细胞，探索神经上皮干细胞向放射状胶质细胞的转变，并梳理分离 它们对大脑皮层的贡献。在这里，我利用来自初级大脑皮质的单细胞RNA测序数据 通过大脑倡议的样本揭示神经干细胞异质性的证据在第一 三个月。通过我的分析已经确定了几个候选基因，这些基因富含 胚胎发育早期的祖细胞。我已经鉴定出两个基因，DLK1和HES4，都是 有趣的是，它们是Notch信号通路中的非规范参与者。DLK1和HES4都是 在从神经上皮干细胞转换为 放射状胶质细胞。使用RNA速度进行的谱系轨迹分析表明，从 神经上皮干细胞簇到放射状胶质细胞簇。当我丰富了影响RNA速度的基因时 其中，DLK1和HES4是影响细胞命运转换的最主要基因。因此，我假设 DLK1和HES4是神经上皮干细胞的标志物，在从 神经上皮干细胞向放射状胶质细胞转化。为了验证我的假设，我将对DLK1进行基因调节 和HES4基因，以确定这些基因在神经上皮细胞中是否必要和/或充分 干细胞生产。

Project Summary/Abstract The human cerebral cortex consists of billions of cells that are primarily generated during developmental stages. During neural development, the neuroepithelium gives rise to radial glia, which is the canonical neural stem cell. Radial glia then asymmetrically divide into transit amplifying intermediate progenitors, which differentiate into excitatory neurons. These steps of neurogenesis have been well characterized in the literature. However, there have been very few studies dedicated to understanding the molecular identity of neuroepithelial stem cells, exploring the transition from neuroepithelial stem cell to radial glia, and teasing apart their contribution to the neocortex. Here I leverage single-cell RNA sequencing data from primary cortical samples through the BRAIN Initiative to reveal evidence of heterogeneity of neural stem cells in the first trimester. Several gene candidates have already been identified through my analyses that are enriched in progenitors during early first trimester development. I have identified two genes, DLK1 and HES4, both of which are interestingly non-canonical players in the Notch signaling pathway. DLK1 and HES4 are both enriched immediately in different progenitor populations before the switch from neuroepithelial stem cell to radial glia. Lineage trajectory analysis using RNA velocity demonstrates a clear putative trajectory from the neuroepithelial stem cell clusters to radial glial clusters. When I enriched for genes that influence RNA velocity the most, DLK1 and HES4 were among the top genes influencing the cell fate switch. Therefore, I hypothesize that DLK1 and HES4 are markers for neuroepithelial stem cells, and are important during the transition from neuroepithelial stem cell to radial glia. To test my hypothesis, I will be performing genetic modulations of DLK1 and HES4 in cerebral organoids to determine if these genes are necessary and/or sufficient in neuroepithelial stem cell production.