State Key Laboratory of Pharmaceutical Biotechnology, MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Institute for Brain Sciences, Nanjing University, Nanjing, Jiangsu Province, China, 210061.
Department of Anesthesiology, The Second Affiliated Hospital, Nanjing Medical University, Nanjing, China, 210003, and.
J Neurosci. 2019 Mar 20;39(12):2195-2207. doi: 10.1523/JNEUROSCI.2523-18.2019. Epub 2019 Jan 28.
The transition of apical progenitors (APs) to basal progenitors (BPs) is an important neurogenic process during cortical expansion. Presenilin enhancer 2 (Pen-2, also named as Psenen) is a key subunit of γ-secretase and has been implicated in neurodevelopmental disease. However, it remains unknown how Pen-2 may regulate the maintenance of APs. To address this question, we generated a conditional KO (cKO) mouse in which Pen-2 is specifically inactivated in neural progenitor cells in the telencephalon. Both male and female embryos were used. We show that cKO cortices display remarkable depletion of Aps, but transient increase on BPs, compared with controls. We demonstrate that the proliferation rate of APs or BPs is not changed, but the switch of APs to BPs is dramatically accelerated in cKO cortices. Molecular analyses reveal decreased levels of Hes1 and Hes5 but increased levels of Ngn2 and NeuroD1 in KO cells. We report that expression of Notch1 intracellular domain in cKO cortices restores the population of APs and BPs. In summary, these findings highlight a central role of the Notch signaling in Pen-2-dependent maintenance of neural stem cells in the developing neocortex. Presenilin enhancer 2 (Pen-2) has been implicated in neurodevelopmental disease. However, mechanisms by which Pen-2 regulates cortical development are not understood. In this study, we generated neural progenitor cell-specific conditional KO mice. We observe depletion of apical progenitors and transiently increased the number of basal progenitors in the developing neocortex of Pen-2 mutant mice. Mechanistic analyses reveal decreased levels of Hes1 and Hes5, but increased levels of neurogenic transcription factors in Pen-2 mutant cortices, compared with controls. We demonstrate that reintroduction of Notch intracellular domain into mutant mice restores the population of apical progenitors to basal progenitors. The above findings strongly suggest that the Pen-2-Notch pathway plays an essential role in the maintenance of neural stem cells during cortical development.
顶侧祖细胞（APs）向基底祖细胞（BPs）的转化是皮质扩张过程中的一个重要神经发生过程。早老素增强子 2（Pen-2，也称为 Psenen）是γ-分泌酶的关键亚基，与神经发育疾病有关。然而，目前尚不清楚 Pen-2 如何调节 APs 的维持。为了解决这个问题，我们在端脑的神经祖细胞中特异性敲除 Pen-2 生成条件性敲除（cKO）小鼠。使用了雄性和雌性胚胎。我们发现与对照组相比，cKO 皮质显示出 APs 的显著耗竭，但 BPs 短暂增加。我们证明 APs 或 BPs 的增殖率没有改变，但在 cKO 皮质中，APs 向 BPs 的转换明显加速。分子分析显示，KO 细胞中的 Hes1 和 Hes5 水平降低，但 Ngn2 和 NeuroD1 水平升高。我们报告 Notch1 细胞内结构域在 cKO 皮质中的表达恢复了 APs 和 BPs 的群体。总之，这些发现强调了 Notch 信号通路在 Pen-2 依赖的发育新皮层神经干细胞维持中的核心作用。早老素增强子 2（Pen-2）与神经发育疾病有关。然而，目前尚不清楚 Pen-2 调节皮质发育的机制。在这项研究中，我们生成了神经祖细胞特异性条件性敲除小鼠。我们观察到 Pen-2 突变小鼠发育中的新皮层中顶侧祖细胞耗竭，基底祖细胞数量短暂增加。与对照组相比，机制分析显示 Pen-2 突变皮质中的 Hes1 和 Hes5 水平降低，但神经发生转录因子的水平升高。我们证明 Notch 细胞内结构域的重新引入到突变小鼠中恢复了 APs 向 BPs 的群体。上述发现强烈表明 Pen-2-Notch 途径在皮质发育过程中维持神经干细胞中起着至关重要的作用。
