In vivo cell signaling dynamics in spinal cord patterning

多细胞生物的发育依赖于广泛的细胞间通讯，这是由少数保守的细胞信号通路介导的。过去30年的研究揭示了不同的信号成分和信号策略。然而，关于细胞信号传导的经典工作要么在生物体外的组织培养中进行，要么不得不依赖于解释静态发育时间点（快照）的事件。这些方法未能捕捉到细胞与许多其他细胞相互作用并随着时间的推移遇到各种信号分子的高度动态的发育性质，特别是因为组织形态发生经常导致广泛的细胞运动。因此，有必要开发体内系统，以了解细胞如何正确整合多种信号，然后在发育中的组织中产生特定和适当的细胞反应。

Development of multicellular organisms relies on extensive cell-to-cell communication, which is mediated by a small number of conserved cell signaling pathways. Studies in the past 30 years have revealed distinct signaling components and signaling strategies. However, classical work on cell signaling has been either carried out in tissue culture outside of living organisms or has had to rely on interpreting events at static developmental time-points (snapshots). These approaches fail to capture the highly dynamic nature of development, where cells interact with many other cells and encounter a variety of signaling molecules over time, especially since tissue morphogenesis often results in extensive cell movements. It is therefore essential to develop in vivo systems to understand how cells can correctly integrate multiple signals and then produce a specific and appropriate cellular response in developing tissues. In my previous published work, I have used the zebrafish spinal cord as a model system to address the importance of cell signaling dynamics in development. Accessibility and optical translucency of zebrafish embryos allows high resolution in vivo real-time imaging of cellular dynamics and cell-cell interactions in live animals. I have demonstrated that the dynamic deployment of both Notch and Hedgehog (Hh) signaling, two key signaling pathways required for animal development, controls the renewal and differentiation of neural progenitors. I have also developed powerful in vivo techniques that allow us to visualize and manipulate cell signaling dynamics in live animals. In our proposed research program, we will utilize in vivo tools to dissect how cell signaling dynamics is regulated at both the molecular and cellular level. In Objective One, we will determine how Hh signaling is terminated at the molecular level upon neuronal differentiation. In Objective Two, we will map the dynamics of Notch signaling in live embryos. The long-term goal of our research program is to elucidate how cell signaling dynamics is regulated in a precise and stereotypic manner to achieve reproducible pattern formation within a living animal.