Transcriptomic analysis of chic embryos forebrain lacking Notch signalling. Gallus gallus

The generation of diverse neuronal types and subtypes from multipotent progenitors during development is crucial for assembling functional neural circuits in the adult central nervous system. It is well known that Notch signalling pathway through the inhibition of proneural genes is a key regulator of neurogenesis in the vertebrate central nervous system. However, its role during hypothalamus formation along with its downstream effectors remains poorly defined. Here, we have transiently blocked Notch activity in chick embryos and used global gene expression analysis to provide evidence that Notch signalling modulates the generation of neurons in the early developing hypothalamus by lateral inhibition. Most importantly, we have taken advantage of this model to identify novel targets of Notch signalling, such as Tagln3 and Chga, which were expressed in hypothalamic neuronal nuclei. This data gives essential advances into the early generation of neurons in the hypothalamus. We demonstrate that inhibition of Notch signalling during early development of the hypothalamus enhances expression of several new markers. These genes must be considered as important new targets of the Notch/proneural network. Overall design: Four sets of samples were used for analysing transcriptome changes in DAPT treated chicl embryos. The rostral part of the head (including the anterior forebrain, optic vesicles and overlying tissue) was collected from control embryos and DAPT-treated embryos at stage HH13.

发育过程中，由多能祖细胞（multipotent progenitors）分化产生多样化的神经元类型与亚型，对于成年中枢神经系统功能性神经环路的构建至关重要。众所周知，通过抑制前神经基因（proneural genes）发挥功能的Notch信号通路（Notch signalling pathway），是脊椎动物中枢神经系统神经发生（neurogenesis）的关键调控因子。然而，该通路在下丘脑形成过程中的作用及其下游效应分子，目前仍未得到充分阐明。
本研究通过瞬时阻断鸡胚内的Notch信号活性，并结合全基因表达分析，证实Notch信号通路可通过侧抑制（lateral inhibition）机制，调控早期发育下丘脑中的神经元生成过程。尤为重要的是，本研究借助该实验模型，鉴定出了Notch信号通路的新型靶基因，例如在下丘脑神经元细胞核中表达的Tagln3与Chga。本研究数据为下丘脑神经元的早期生成研究提供了重要进展。
我们证实，在下丘脑早期发育阶段阻断Notch信号通路，可上调多个新型标记基因的表达水平。上述基因可被视为Notch/前神经网络的重要新型靶标。
实验设计概述：本研究设置四组样本，用于分析DAPT处理鸡胚的转录组变化。于HH13期，分别从对照组与DAPT处理组鸡胚中收集头部吻侧区域（包含前脑前部、视泡及其覆盖组织）。