Cell signaling crosstalk during spinal cord patterning

多细胞生物的发育依赖于广泛的细胞间通讯，这是由少量保守的细胞信号传导途径介导的。过去 30 年的研究揭示了不同的信号成分和信号策略。然而，细胞信号传导的经典工作是在培养细胞中进行的，或者依赖于解释静态发育时间点（快照）的事件。这些方法通常无法捕获发育过程的高度动态性质，其中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，特别是因为组织形态发生通常会导致广泛的细胞运动。因此，开发体内系统以了解细胞如何正确整合多个信号以产生特定的细胞反应至关重要。我们研究计划的长期目标是阐明如何整合多个细胞信号通路的动态相互作用以实现胚胎中精确的模式形成。我的实验室使用斑马鱼脊髓作为模型系统来研究细胞信号串扰的重要性。斑马鱼胚胎的可接近性和光学半透明性允许对活体动物的细胞动力学和细胞间相互作用进行高分辨率体内成像。结合光可转换细胞信号报告基因和基因操作，我们最近证明Notch信号通过控制Gli转录因子的表达来维持脊髓中神经祖细胞的Hedgehog（Hh）反应性。此外，Notch 信号传导的持续时间在腹侧脊髓的时间规范中起着指导作用。基于我们最近的工作，我们假设 Notch 信号通过 Gli 依赖性机制维持神经祖细胞的 Hh 反应性，并且 Notch/Hh 反应的持续时间决定细胞命运。在我们提出的研究计划中，我们将剖析 Notch 和 Hh 信号之间的串扰如何有助于脊髓的可重复模式。我们将实现三个目标：1）确定 Notch 和 Hh 信号传导的持续时间如何调节脊髓模式； 2) 确定Notch信号是否调节Gli转录因子的稳定性或纤毛运输； 3) 开发新的体内工具，以单细胞分辨率可视化 Notch/Hh 信号动力学。我们的研究计划将共同揭示细胞信号串扰如何在体内调节以及组织如何以精确和可重复的方式形成图案的基本原理。

Development of multicellular organisms relies on extensive cell-to-cell communications, which are 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 carried out in cultured cells or relied on interpreting events at static developmental time-points (snapshots). These approaches are often unable to capture the highly dynamic nature of developmental processes, 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 correctly integrate multiple signals to produce specific cellular responses. The long-term goal of our research program is to elucidate how the dynamic interactions of multiple cell signaling pathways are integrated to achieve precise pattern formation in the embryo. My lab uses the zebrafish spinal cord as a model system to study the importance of cell signaling crosstalk. Accessibility and optical translucency of zebrafish embryos allows high resolution in vivo imaging of cellular dynamics and cell-cell interactions in live animals. Combining photo-convertible cell signaling reporters and genetic manipulations, we have recently demonstrated that Notch signaling maintains Hedgehog (Hh) responsiveness of neural progenitors in the spinal cord by controlling the expression of Gli transcription factors. Moreover, the duration of Notch signaling plays an instructive role in temporal specification of the ventral spinal cord. Building upon our recent work, we hypothesize that Notch signaling maintains Hh responsiveness of neural progenitors via a Gli-dependent mechanism and the duration of Notch/Hh response determines the cell fate. In our proposed research program, we will dissect how the crosstalk between Notch and Hh signaling contributes to reproducible patterning of the spinal cord. In three objectives, we will: 1) determine how the duration of Notch and Hh signaling regulates spinal cord patterning; 2) determine whether Notch signaling regulates the stability or ciliary trafficking of Gli transcription factors; and 3) develop new in vivo tools to visualize Notch/Hh signaling dynamics at the single-cell resolution. Together, our research program will reveal fundamental principles of how cell signaling crosstalk is regulated in vivo and how tissue is patterned in a precise and reproducible manner.