Wang Junbao, Wang Andi, Tian Kuan, Hua Xiaojiao, Zhang Bo, Zheng Yue, Kong Xiangfei, Li Wei, Xu Lichao, Wang Juan, Li Zhiqiang, Liu Ying, Zhou Yan
Department of Neurosurgery, Zhongnan Hospital of Wuhan University; Frontier Science Center for Immunology and Metabolism, Medical Research Institute at School of Medicine; The RNA Institute, College of Life Sciences; Wuhan University, Wuhan, Hubei, China.
Department of Neurology, Wuhan Central Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.
Cell Discov. 2022 Aug 2;8(1):74. doi: 10.1038/s41421-022-00421-2.
β-catenin-dependent canonical Wnt signaling plays a plethora of roles in neocortex (Ncx) development, but its function in regulating the abundance of intermediate progenitors (IPs) is elusive. Here we identified neCtnnb1, an evolutionarily conserved cis-regulatory element with typical enhancer features in developing Ncx. neCtnnb1 locates 55 kilobase upstream of and spatially close to the promoter of Ctnnb1, the gene encoding β-catenin. CRISPR/Cas9-mediated activation or interference of the neCtnnb1 locus enhanced or inhibited transcription of Ctnnb1. neCtnnb1 drove transcription predominantly in the subventricular zone of developing Ncx. Knock-out of neCtnnb1 in mice resulted in compromised expression of Ctnnb1 and the Wnt reporter in developing Ncx. Importantly, knock-out of neCtnnb1 lead to reduced production and transit-amplification of IPs, which subsequently generated fewer upper-layer Ncx projection neurons (PNs). In contrast, enhancing the canonical Wnt signaling by stabilizing β-catenin in neCtnnb1-active cells promoted the production of IPs and upper-layer Ncx PNs. ASH2L was identified as the key trans-acting factor that associates with neCtnnb1 and Ctnnb1's promoter to maintain Ctnnb1's transcription in both mouse and human Ncx progenitors. These findings advance understanding of transcriptional regulation of Ctnnb1, and provide insights into mechanisms underlying Ncx expansion during development.
β-连环蛋白依赖性经典Wnt信号通路在新皮层（Ncx）发育中发挥着众多作用，但其在调节中间祖细胞（IPs）数量方面的功能尚不清楚。在这里，我们鉴定了neCtnnb1，这是一种在发育中的Ncx中具有典型增强子特征的进化保守顺式调控元件。neCtnnb1位于编码β-连环蛋白的基因Ctnnb1启动子上游55千碱基处，且在空间上与之接近。CRISPR/Cas9介导的neCtnnb1位点激活或干扰增强或抑制了Ctnnb1的转录。neCtnnb1主要在发育中的Ncx的脑室下区驱动转录。敲除小鼠中的neCtnnb1导致发育中的Ncx中Ctnnb1和Wnt报告基因的表达受损。重要的是，敲除neCtnnb1导致IPs的产生和过渡扩增减少，随后产生的上层Ncx投射神经元（PNs）也减少。相反，通过在neCtnnb1活性细胞中稳定β-连环蛋白来增强经典Wnt信号通路，可促进IPs和上层Ncx PNs的产生。ASH2L被确定为关键的反式作用因子，它与neCtnnb1和Ctnnb1的启动子结合，以维持小鼠和人类Ncx祖细胞中Ctnnb1的转录。这些发现推进了对Ctnnb1转录调控的理解，并为发育过程中Ncx扩展的潜在机制提供了见解。
