Progenitors resume generating neurons after temporary inhibition of neurogenesis by Notch activation in the mammalian cerebral cortex
Progenitors resume generating neurons after temporary inhibition of neurogenesis by Notch activation in the mammalian cerebral cortex
复制标题
DOI：
10.1242/dev.01693
复制
发表时间：
2005-03-01
期刊：
影响因子：
4.6
通讯作者：
Saito, T
中科院分区：
文献类型：
--
作者：
Mizutani, K;Saito, T
哺乳动物的大脑皮层由六层神经元组成。脑室区的皮质祖细胞通过连续的细胞分裂产生对每一层特异的神经元。第VI层的神经元在早期阶段产生，而后来出生的神经元逐渐占据上层。然而，神经发生的潜在分子机制相对未知。在这项研究中，我们设计了一个系统，其中Notch通路在皮层中通过体内电穿孔和Cre介导的DNA重组被时空激活。在E13.5的电穿孔将DNA转移到早期祖细胞，这些祖细胞产生下层和上层的神经元。在E13.5时强制表达Notch的组成型活性形式（caNotch）抑制祖细胞产生神经元，并使祖细胞保持为增殖的放射状胶质细胞。随后在E15.5转染Cre表达载体以去除caNotch后，其中切除caNotch的双转染细胞迁移到皮质板中并分化成对上层特异性的神经元。溴脱氧尿苷标记实验显示Cre转染后有神经元产生。这些结果表明，在早期阶段暂时经历Notch激活的皮质祖细胞在后期阶段产生神经元，但跳过了低层神经元的产生。此外，双转染的细胞产生上层神经元，即使在它们移植到E13.5脑中之后，也表明祖细胞的发育状态不被caNotch活性停止。
The mammalian cerebral cortex comprises six layers of neurons. Cortical progenitors in the ventricular zone generate neurons specific to each layer through successive cell divisions. Neurons of layer VI are generated at an early stage, whereas later-bom neurons occupy progressively upper layers. The underlying molecular mechanisms of neurogenesis, however, are relatively unknown. In this study, we devised a system where the Notch pathway was activated spatiotemporally in the cortex by in vivo electroporation and Cre-mediated DNA recombination. Electroporation at E13.5 transferred DNA to early progenitors that gave rise to neurons of both low and upper layers. Forced expression of a constitutively active form of Notch (caNotch) at E13.5 inhibited progenitors from generating neurons and kept progenitors as proliferating radial glial cells. After subsequent transfection at E15.5 of a Cre expression vector to remove caNotch, doubletransfected cells, in which caNotch was excised, migrated into the cortical plate and differentiated into neurons specific to upper layers. Bromodeoxyuridine-labeling experiments showed that the neurons were born after Cre transfection. These results indicate that cortical progenitors that had been temporarily subjected to Notch activation at an early stage generated neurons at later stages, but that the generation of low-layer neurons was skipped. Moreover, the double-transfected cells gave rise to upper-layer neurons, even after their transplantation into the E13.5 brain, indicating that the developmental state of progenitors is not halted by caNotch activity.