Controlling collective behavior in eukaryotic cell populations

描述（由申请人提供）：本提案的总体目标是了解单细胞的非线性时空动力学如何在社会变形虫盘状盘形虫（Dictyostelium disideum）的多细胞阶段引起相干行为。我们将通过高精度测量和数学建模的结合来实现这一目标。在这个系统中，饥饿的变形虫参与了一个发展程序，作为一种替代的生存策略。单个细胞通过信号分子cAMP进行交流，cAMP作为趋化性的线索，导致细胞聚集并形成多细胞黏菌。本提案的具体目标是：(1)获得单细胞cAMP信号的定量描述，(2)了解单细胞梯度传感及其与cAMP信号传导的关系，以及(3)建立一个多细胞模型，概括Dictyostelium细胞群体中观察到的集体行为。开发这些模型将回答三个基本问题：表征细胞cAMP信号动力学的单个细胞的基本自由度是什么？细胞外梯度感应如何与细胞质cAMP水平相关？如何从细胞内和细胞间的cAMP信号动力学推断出大规模的多细胞时空信号模式和细胞聚集？回答这些问题将扩大我们对分子信号和细胞相互作用如何导致集体多细胞行为的理解，并最终指导我们找到控制这些行为的方法。从实际的角度来看，这一建议建立在我们发明的一套新方法的基础上，这些方法使我们能够成功地监测单个细胞中信号分子cAMP的细胞内和细胞外浓度。社会性变形虫为实验驱动的定量建模提供了一个独特的机会，因为它们允许在单细胞和多细胞水平上同时进行测量；细胞可以被限制在高度可控的微流体环境中，并且从遗传数据库中可以获得许多信号和聚集突变体。从广泛的角度来看，这项研究可能会产生新的实验和定量工具来分析细胞间的信号传导和新的突发行为的单细胞到多细胞的转变。

DESCRIPTION (provided by applicant): The overall goal of this proposal is to understand how nonlinear spatio-temporal dynamics of single cells give rise to coherent behaviors at the multi-cell stage in the social amoeba Dictyostelium discoideum. We will achieve this through a combination of high-precision measurements and mathematical modeling. In this system, starved amoebae engage in a developmental program as an alternate survival strategy. Individual cells communicate via the signaling molecule cAMP, which serves as a cue for chemotaxis that leads cells to aggregate and form a multi-cellular slime mold. The specific goals of this proposal are (1) to obtain a quantitative description for single cell cAMP signaling, (2) to understand single cell gradient sensing and its relationship to cAMP signaling, and (3) to develop a multi-cell model that recapitulates observed collective behaviors in Dictyostelium cell populations. Developing these models will answer three fundamental questions: What are the essential degrees of freedom of individual cells that characterize the cell's cAMP signaling dynamics? How extra-cellular gradient sensing is linked to cytosolic cAMP levels? How can large-scale multi- cellular spatio-temporal signaling patterns and cellular aggregation be inferred from intra- and inter-cellular cAMP signaling dynamics? Answering these questions will expand our understanding of how molecular signaling and cellular interactions lead to collective multi-cellular behaviors, and ultimately guide us to find ways to control such behaviors. From a practical point of view, this proposal builds on a new set of methods we have invented that have enabled us to successfully monitor both intra- and extra-cellular concentrations of the signaling molecule cAMP in individual cells. Social amoebae provide a unique opportunity for experiment- driven quantitative modeling because they allow for measurements simultaneously at the single cell and at the multi-cell levels; cells can be confined into highly controllable microfluidic environments and numerous signaling and aggregation mutants are available from a genetic databank. From a broad perspective, the research is likely to yield new experimental and quantitative tools for analyzing cell-to-cell signaling and the single-to-multi-cell transition of novel emergent behaviors.