Department of Medical Neurobiology, Institute of Medical Research Israel-Canada (IMRIC) and the Edmond and Lily Safra Center for Brain Sciences (ELSC), Hebrew University of Jerusalem-Hadassah Medical School, P.O.Box 12272, 9112102, Jerusalem, Israel.
Centre for Cancer Biology, University of South Australia and SA Pathology, North Terrace, Adelaide, SA, 5001, Australia.
BMC Biol. 2021 Apr 23;19(1):84. doi: 10.1186/s12915-021-01014-3.
The dorsal domain of the neural tube is an excellent model to investigate the generation of complexity during embryonic development. It is a highly dynamic and multifaceted region being first transiently populated by prospective neural crest (NC) cells that sequentially emigrate to generate most of the peripheral nervous system. Subsequently, it becomes the definitive roof plate (RP) of the central nervous system. The RP, in turn, constitutes a patterning center for dorsal interneuron development. The factors underlying establishment of the definitive RP and its segregation from NC and dorsal interneurons are currently unknown.
We performed a transcriptome analysis at trunk levels of quail embryos comparing the dorsal neural tube at premigratory NC and RP stages. This unraveled molecular heterogeneity between NC and RP stages, and within the RP itself. By implementing these genes, we asked whether Notch signaling is involved in RP development. First, we observed that Notch is active at the RP-interneuron interface. Furthermore, gain and loss of Notch function in quail and mouse embryos, respectively, revealed no effect on early NC behavior. Constitutive Notch activation caused a local downregulation of RP markers with a concomitant development of dI1 interneurons, as well as an ectopic upregulation of RP markers in the interneuron domain. Reciprocally, in mice lacking Notch activity, both the RP and dI1 interneurons failed to form and this was associated with expansion of the dI2 population.
Collectively, our results offer a new resource for defining specific cell types, and provide evidence that Notch is required to establish the definitive RP, and to determine the choice between RP and interneuron fates, but not the segregation of RP from NC.
神经管的背侧区域是研究胚胎发育过程中产生复杂性的极佳模型。它是一个高度动态和多方面的区域，最初短暂地被未来的神经嵴（NC）细胞占据，这些细胞随后依次迁移以生成大部分周围神经系统。随后，它成为中枢神经系统的明确顶板（RP）。反过来，RP 构成了背侧中间神经元发育的模式中心。目前尚不清楚确立明确的 RP 及其与 NC 和背侧中间神经元分离的因素。
我们在比较迁移前 NC 和 RP 阶段的禽类胚胎的躯干水平进行了转录组分析。这揭示了 NC 和 RP 阶段之间以及 RP 本身之间的分子异质性。通过实施这些基因，我们询问 Notch 信号是否参与 RP 发育。首先，我们观察到 Notch 在 RP-中间神经元界面处活跃。此外，在禽类和小鼠胚胎中分别获得和丧失 Notch 功能，对早期 NC 行为没有影响。组成型 Notch 激活导致 RP 标记物的局部下调，同时在中间神经元区域发育出 dI1 中间神经元，以及 RP 标记物的异位上调。相反，在缺乏 Notch 活性的小鼠中，RP 和 dI1 中间神经元均未形成，这与 dI2 群体的扩张有关。
总的来说，我们的结果为定义特定细胞类型提供了新的资源，并提供了证据表明 Notch 是建立明确的 RP 所必需的，并决定了 RP 和中间神经元命运之间的选择，而不是 RP 与 NC 的分离。
