Astrocytes regulate brain-wide functions and also show region-specific differences, but little is known about how general and region-specific functions are aligned at the single-cell level. To explore this, we isolated adult mouse diencephalic astrocytes by ACSA-2-mediated magnetic-activated cell sorting (MACS). Single-cell RNA-seq revealed 7 gene expression clusters of astrocytes, with 4 forming a supercluster. Within the supercluster, cells differed by gene expression related to ion homeostasis or metabolism, with the former sharing gene expression with other regions and the latter being restricted to specific regions. All clusters showed expression of proliferation-related genes, and proliferation of diencephalic astrocytes was confirmed by immunostaining. Clonal analysis demonstrated low level of astrogenesis in the adult diencephalon, but not in cerebral cortex grey matter. This led to the identification of Smad4 as a key regulator of diencephalic astrocyte in vivo proliferation and in vitro neurosphere formation. Thus, astrocytes show diverse gene expression states related to distinct functions with some subsets being more widespread while others are more regionally restricted. However, all share low-level proliferation revealing the novel concept of adult astrogenesis in the diencephalon.

中文翻译：

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间脑星形胶质细胞的分子多样性揭示了 Smad4 调控的成年星形发生

星形胶质细胞调节整个大脑的功能，也显示出区域特异性的差异，但对于一般和区域特异性功能如何在单细胞水平上对齐，我们知之甚少。为了探索这一点，我们通过 ACSA-2 介导的磁激活细胞分选 (MACS) 分离了成年小鼠间脑星形胶质细胞。单细胞 RNA-seq 揭示了 7 个星形胶质细胞基因表达簇，其中 4 个形成了一个超簇。在超集群内，细​​胞因与离子稳态或代谢相关的基因表达而异，前者与其他区域共享基因表达，后者仅限于特定区域。所有簇均表达增殖相关基因，免疫染色证实间脑星形胶质细胞增殖。克隆分析表明成年间脑中的星形发生水平较低，但不在大脑皮层灰质中。这导致 Smad4 被鉴定为间脑星形胶质细胞的关键调节因子体内增殖和体外神经球形成。因此，星形胶质细胞显示出与不同功能相关的不同基因表达状态，其中一些子集更广泛，而其他子集则更受区域限制。然而，所有这些都具有低水平的增殖，揭示了间脑中成人星形发生的新概念。