Zeb2 is Essential for Bergmann Glial Development and Cerebellar Organization

Cerebellar circuitry is critical for balance and motor control among a wide array of functions and largely consists of granule and Purkinje neurons. Bergmann glia in the cerebellum form distinct morphological structures that facilitate granule neuron migration during development and that maintain the cerebellar organization and functional integrity. At present, molecular control of the formation and morphogenesis of Bergmann glia remains obscure. In this study, we found that Zeb2 (a.k.a. Sip1 or Zfhx1b), a Mowat-Wilson syndrome-associated transcriptional regulator, is highly restricted to Bergmann glia and is essential for their development and maturation. The mice with Zeb2 ablation in the cerebellar neural progenitor exhibit dysgenesis of cerebellar cortical lamination and locomotion defects. Deletion of Zeb2 markedly reduced Bergmann glial proliferation, differentiation and the establishment of the normal radial scaffold, disrupting migration of granule cell progenitors from external to internal granular layers. Transcriptome profiling indicated that Zeb2 regulates multiple pathways including FGF and Notch signaling as well as axonal guidance cues including Netrin G2 and Gdf10 to control Bergmann glial development. Our data reveal that Zeb2 acts as a transcriptional integrator of diverse signaling pathways to regulate the formation and morphogenesis of Bergmann glia ensuring maintenance of cerebellar integrity, suggesting that Zeb2 dysfunction in Bergmann glia might contribute to motor deficits in Mowat-Wilson syndrome. 6 RNA-Seq samples from P0 cerebellum of Ctrl and Zeb2 CKO mice (3 Ctrl and 3 CKO).小脑环路在诸多生理功能中对平衡与运动控制发挥关键作用，其主要由颗粒细胞与浦肯野神经元构成。小脑内的伯格曼胶质细胞（Bergmann glia）可形成独特的形态结构，在发育阶段促进颗粒神经元迁移，并维持小脑的组织结构与功能完整性。目前，伯格曼胶质细胞的形成与形态发生的分子调控机制仍不明晰。本研究发现，Zeb2（别名Sip1或Zfhx1b）——一种与莫-威综合征（Mowat-Wilson syndrome）相关的转录调控因子——特异性高表达于伯格曼胶质细胞，且对其发育与成熟不可或缺。在小脑神经前体细胞中敲除Zeb2的小鼠，会出现小脑皮层分层发育异常以及运动功能缺陷。敲除Zeb2会显著降低伯格曼胶质细胞的增殖、分化能力以及正常放射状支架的建立，进而干扰颗粒细胞前体从外颗粒层向内颗粒层的迁移过程。转录组测序（RNA-Seq）分析显示，Zeb2可调控多条信号通路，包括成纤维细胞生长因子（FGF）与Notch信号通路，同时调控Netrin G2、Gdf10等轴突导向分子，以此调控伯格曼胶质细胞的发育。本研究数据揭示，Zeb2作为多种信号通路的转录整合因子，通过调控伯格曼胶质细胞的形成与形态发生以维持小脑结构完整性；这提示伯格曼胶质细胞中Zeb2功能异常可能参与莫-威综合征患者的运动功能障碍。本研究包含6例来自出生后0天（P0）小鼠小脑的RNA测序样本，其中对照组（Ctrl）与Zeb2条件性敲除（CKO）小鼠各3例。