Department of Biochemistry and Cellular Biology, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo 187-8551, Japan.
Department of Life Science and Medical Bioscience, School of Advanced Science and Engineering, Waseda University, Tokyo 169-8555, Japan.
eNeuro. 2021 May 12;8(3). doi: 10.1523/ENEURO.0468-20.2021. Print 2021 May-Jun.
Cerebellar granule cells (GCs) are cells which comprise over 50% of the neurons in the entire nervous system. GCs enable the cerebellum to properly regulate motor coordination, learning, and consolidation, in addition to cognition, emotion and language. During GC development, maternal GC progenitors (GCPs) divide to produce not only postmitotic GCs but also sister GCPs. However, the molecular machinery for regulating the proportional production of distinct sister cell types from seemingly uniform GCPs is not yet fully understood. Here we report that Notch signaling creates a distinction between GCPs and leads to their proportional differentiation in mice. Among Notch-related molecules, , , , and are prominently expressed in GCPs. monitoring of -promoter activities showed the presence of two types of GCPs, Notch-signaling ON and OFF, in the external granule layer (EGL). Single-cell RNA sequencing (scRNA-seq) and analyses indicate that ON-GCPs have more proliferative and immature properties, while OFF-GCPs have opposite characteristics. Overexpression as well as knock-down (KD) experiments using electroporation showed that NOTCH2 and HES1 are involved cell-autonomously to suppress GCP differentiation by inhibiting NEUROD1 expression. In contrast, JAG1-expressing cells non-autonomously upregulated Notch signaling activities via NOTCH2-HES1 in surrounding GCPs, eventually suppressing their differentiation. These findings suggest that Notch signaling results in the proportional generation of two types of cells, immature and differentiating GCPs, which contributes to the well-organized differentiation of GCs.
小脑颗粒细胞 (GCs) 是构成整个神经系统中超过 50%神经元的细胞。GCs 使小脑能够正确调节运动协调、学习和巩固，以及认知、情感和语言。在 GC 发育过程中，母代 GC 祖细胞 (GCPs) 分裂不仅产生有丝分裂后的 GCs，还产生姐妹 GCPs。然而，调节从看似均匀的 GCP 中产生不同姐妹细胞类型的比例的分子机制尚不完全清楚。在这里，我们报告 Notch 信号在小鼠中创建了 GCP 之间的区别，并导致它们的比例分化。在 Notch 相关分子中，Notch1、DLL1、Jag1 和 Hes1 在 GCPs 中表达明显。Notch 报告基因的启动子活性监测显示，外颗粒层 (EGL) 中有两种类型的 GCP，即 Notch 信号开启和关闭。单细胞 RNA 测序 (scRNA-seq) 和谱系追踪分析表明，ON-GCP 具有更多的增殖和不成熟特性，而 OFF-GCP 具有相反的特性。过表达以及使用 电穿孔进行的 KD 实验表明，NOTCH2 和 HES1 通过抑制 NEUROD1 表达，细胞自主地参与抑制 GCP 分化。相比之下，表达 JAG1 的细胞通过周围 GCP 中的 NOTCH2-HES1 非自主地上调 Notch 信号活性，最终抑制它们的分化。这些发现表明 Notch 信号导致两种类型的细胞，即不成熟和分化的 GCPs，按比例产生，这有助于 GCs 的有序分化。
