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

发育和再生过程中的组织模式化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，被称为形态发生素， 细胞知道他们在哪里，他们应该成为什么。最近的研究表明， 形态发生素空间分布和它们的细胞内信号传导活性是高度时间依赖性的， 这些动态特征对于个体细胞的命运决定和组织图案化是至关重要的。 细胞群。这是生物学中的一个核心挑战，即了解离散细胞的命运 并且使用由高度编码的定量信息来实现精确的组织图案化。 动态形态发生信号。神经系统提供了一个迷人的例子， 来自几种形态发生素的输入，产生不同的细胞类型和复杂的模式。虽然各大 已经发现了参与神经发育的形态发生素，它们的时空动态和 由于缺乏直接的， 在体内单个细胞水平上的信号传导的动态分析和操纵。 为了克服这些限制，我开发了一种新的组织工程技术， 形态发生梯度和模式，以在体外形成。我还采用了新的胚胎干细胞技术 胚胎干细胞（ESC）分化，使神经发育的分析非常相似， 在体内发生在适合高分辨率定量分析的系统中。结合我们 创新的单细胞延时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 解码）。在K99阶段，我将专注于 形态基元Sonic Hedgehog（Shh），这是在所有区域中指定腹侧神经类型所必需的 发育中的神经管我将系统地回答以下问题：（1）如何 动态Shh信号梯度产生和转导形成模式？(2)建筑如何 Shh通路的特征影响信号动力学和模式行为？(3)的哪些方面 下行信号解码机制的设计决定了解码的精度和保真度。 细胞反应和模式形成在R 00阶段，我将扩展平台，以研究如何 协调来自多个梯度的信号的时空动力学，例如Shh和RA（视黄酸）， 酸），可以使细胞命运多样化，以允许在神经管中形成复杂的图案。所有这些 结果将提供一个全面的了解时空之间的关系， 形态梯度和组织模式的动态，以及定量框架， 精确控制体外ES/iPS细胞向自身图案化组织的分化。

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.