Spatio-Temporal Signaling Dynamics in Neuronal Cell Fate Decision and Patterning

在发育和再生过程中的组织构图需要一致的细胞命运决定 空间和时间。分泌的、可扩散的分子，被称为形态生成物，为 细胞知道它们在哪里以及它们应该变成什么样子。最近的研究表明， 形态原的空间分布及其细胞内信号活动高度依赖于时间，并且 这些动态特征对于单个细胞中的命运决定和整个组织的构图至关重要 细胞数量。这是生物学中的一个核心挑战，即了解离散细胞如何命运 和精确的组织图案使用高度编码的定量信息来实现 动态形态信号。神经系统提供了一个令人着迷的及时信号的例子 来自产生不同细胞类型和复杂模式的几种形态来源的输入。虽然少校 参与神经发育的形态因子已被发现，它们的时空动力学和 精确信号解释的机制由于缺乏直接的、 体内单个细胞水平信号的动态分析和处理。 为了克服这些限制，我开发了一种新的组织工程学技术，可以 形态梯度和花纹在体外形成。我还采用了胚胎干细胞的新方法。 细胞(ESC)分化，使神经发育分析非常类似于 在体内发生的，在一个服从高分辨率定量分析的系统中。与我们的 创新的单细胞时间推移成像和基因表达分析、基因电路工程和 数学建模，我将揭示控制时空的机制 细胞内信号的动力学(时间编码)及其解释(时间 译码)在神经前体细胞指定期间。在K99阶段，我将专注于 形态原Sonic Hedgehog(Shh)，它对于指定所有区域的腹神经类型是必不可少的 发育中的神经管。我将系统地回答以下问题：(1)如何 动态Shh信号梯度的产生和传递以形成模式？(2)建筑如何 Shh通路的特征影响信号动力学和模式行为？(3)哪些方面 下行信号译码机构的设计决定了译码的精度和保真度 细胞反应和图案形成？在R00阶段，我将扩展平台以检查如何 协调来自多个梯度的信号的时空动力学，例如Shh和RA(维甲酸 酸)，可以使细胞命运多样化，从而在神经管中形成复杂的模式。加在一起，这些 这些结果将提供对时空之间关系的全面理解 形态梯度和组织图案化的动力学，以及 在体外精确控制ES/iPS细胞向自体图案组织的分化。

Tissue patterning during development and regeneration requires consistent cell fate decisions in space and time. Secreted, diffusible molecules, named morphogens, set up the spatial coordinates for cells to know where they are and what they should become. Recent studies have revealed that the spatial profile of morphogens and their intracellular signal activities are highly time-dependent, and these dynamic features are essential for fate decisions in individual cells and tissue patterning across a population of cells. This presents a central challenge in biology to understand how discrete cell fates and precise tissue patterning are achieved using the quantitative information encoded by the highly dynamic morphogen signals. The neural system provides a fascinating example of well-timed signal inputs from several morphogens generating diverse cell types and intricate patterns. Although the major morphogens involved in neural development have been discovered, their spatio-temporal dynamics and the mechanism of precise signal interpretation have been largely overlooked due to the lack of direct, dynamic analysis and manipulation of signaling at the level of individual cells in vivo. To overcome these limitations, I have developed a novel tissue engineering technique allowing morphogen gradient and patterns to form in vitro. I have also adapted new methods for embryonic stem cell (ESC) differentiation that enable the analysis of neural development closely resembling those occurring in vivo in a system amenable to high resolution quantitative analysis. In combination with our innovative single cell time-lapse imaging and gene expression analysis, genetic circuit engineering and mathematical modeling, I will reveal the mechanisms that control both the spatio-temporal dynamics of intracellular signals (temporal encoding) and their interpretation (temporal decoding) during neural progenitor cell specification. During K99 phase, I will focus on the morphogen Sonic Hedgehog (Shh), which is essential for specifying ventral neural types in all regions of the developing neural tube. I will systematically address the following questions: (1) How are dynamic Shh signaling gradients produced and transduced to form pattern? (2) How do architectural features of the Shh pathway affect signaling dynamics and patterning behavior? (3) What aspects of the design of downstream signal decoding mechanism determine the precision and fidelity of the cellular response and pattern formation? During R00 phase, I will expand the platform to examine how coordinating spatiotemporal dynamics of signals from multiple gradients, such as Shh and RA (retinoic acid), can diversify cell fates to allow complex pattern formation in the neural tube. Together, these results will provide a comprehensive understanding of the relationship between spatio-temporal dynamics of morphogen gradients and tissue patterning, as well as a quantitative framework for precisely controlling in vitro ES/iPS cell differentiation towards self-patterned tissue.