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

项目总结/摘要 人类大脑皮层由数十亿个细胞组成，这些细胞主要在发育过程中产生。 阶段在神经发育过程中，神经上皮产生放射状胶质细胞，这是典型的神经胶质细胞。 干细胞放射状胶质细胞然后不对称地分裂成转运扩增中间祖细胞， 分化成兴奋性神经元。神经发生的这些步骤已经在 文学然而，很少有研究致力于了解 神经上皮干细胞，探索从神经上皮干细胞到放射状神经胶质细胞的过渡， 他们对大脑皮层的贡献在这里，我利用来自初级皮质的单细胞RNA测序数据， 样本通过大脑倡议，以揭示证据的异质性神经干细胞在第一次 三个月通过我的分析，已经确定了几个候选基因，它们富含 在早期的前三个月发展的祖细胞。我已经确定了两个基因，DLK 1和HES 4， 它们是Notch信号通路中有趣的非典型参与者。DLK 1和HES 4都是 在从神经上皮干细胞转换为神经干细胞之前， 放射状胶质细胞。使用RNA速度的谱系轨迹分析显示了从RNA水平的清晰的推定轨迹。 神经上皮干细胞簇到放射状胶质细胞簇。当我富集影响RNA速度的基因时， DLK 1和HES 4是影响细胞命运转换的主要基因。因此，我假设 DLK 1和HES 4是神经上皮干细胞的标志物，在从神经上皮干细胞向神经上皮干细胞转化的过程中很重要。 神经上皮干细胞到放射状胶质细胞。为了验证我的假设，我将对DLK 1进行基因调节 和HES 4，以确定这些基因在神经上皮细胞中是否是必要的和/或足够的。 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.