Institute of Neuroscience, National Yang-Ming University, Taipei, Taiwan, Republic of China ; Graduate Institute of Basic Medical Science, China Medical University, Taichung, Taiwan, Republic of China ; Graduate Institute of Molecular Systems Biomedicine, China Medical University, Taichung, Taiwan, Republic of China.
PLoS One. 2013 Sep 20;8(9):e74975. doi: 10.1371/journal.pone.0074975. eCollection 2013.
Nolz-1, as a murine member of the NET zinc-finger protein family, is expressed in post-mitotic differentiating neurons of striatum during development. To explore the function of Nolz-1 in regulating the neurogenesis of forebrain, we studied the effects of ectopic expression of Nolz-1 in neural progenitors. We generated the Cre-loxP dependent conditional transgenic mice in which Nolz-1 was ectopically expressed in proliferative neural progenitors. Ectopic expression of Nolz-1 in neural progenitors by intercrossing the Nolz-1 conditional transgenic mice with the nestin-Cre mice resulted in hypoplasia of telencephalon in double transgenic mice. Decreased proliferation of neural progenitor cells were found in the telencephalon, as evidenced by the reduction of BrdU-, Ki67- and phospho-histone 3-positive cells in E11.5-12.5 germinal zone of telencephalon. Transgenic Nolz-1 also promoted cell cycle exit and as a consequence might facilitate premature differentiation of progenitors, because TuJ1-positive neurons were ectopically found in the ventricular zone and there was a general increase of TuJ1 immunoreactivity in the telencephalon. Moreover, clusters of strong TuJ1-expressing neurons were present in E12.5 germinal zone. Some of these strong TuJ1-positive clusters, however, contained apoptotic condensed DNA, suggesting that inappropriate premature differentiation may lead to abnormal apoptosis in some progenitor cells. Consistent with the transgenic mouse analysis in vivo, similar effects of Nozl-1 over-expression in induction of apoptosis, inhibition of cell proliferation and promotion of neuronal differentiation were also observed in three different N18, ST14A and N2A neural cell lines in vitro. Taken together, our study indicates that ectopic expression of Nolz-1 in neural progenitors promotes cell cycle exit/premature neuronal differentiation and induces abnormal apoptosis in the developing telencephalon.
Nolz-1 作为 NET 锌指蛋白家族的一个鼠类成员，在发育过程中表达于纹状体的有丝后分化神经元中。为了研究 Nolz-1 调节前脑神经发生的功能，我们研究了 Nolz-1 在神经前体细胞中的异位表达效应。我们通过将 Nolz-1 条件性转基因小鼠与 nestin-Cre 小鼠杂交，产生了 Cre-loxP 依赖性条件性转基因小鼠，使 Nolz-1 在增殖性神经前体细胞中异位表达。神经前体细胞中 Nolz-1 的异位表达导致双转基因小鼠的端脑发育不全。通过在 E11.5-12.5 端脑生发区减少 BrdU、Ki67 和磷酸化组蛋白 3 阳性细胞，发现神经前体细胞的增殖减少。转 Nolz-1 也促进了细胞周期退出，因此可能促进了祖细胞的过早分化，因为 TuJ1 阳性神经元在脑室区异位出现，并且在端脑中普遍增加了 TuJ1 免疫反应性。此外，在 E12.5 生发区存在强烈的 TuJ1 表达神经元簇。然而，一些强 TuJ1 阳性簇包含凋亡性浓缩 DNA，这表明不合适的过早分化可能导致一些祖细胞的异常凋亡。与体内转基因小鼠分析一致，在体外三种不同的 N18、ST14A 和 N2A 神经细胞系中，也观察到 Nozl-1 过表达在诱导凋亡、抑制细胞增殖和促进神经元分化方面的类似效应。综上所述，我们的研究表明，神经前体细胞中 Nolz-1 的异位表达促进了细胞周期退出/过早的神经元分化，并导致发育中的端脑异常凋亡。
