Mechanisms of robustness in organogenesis

项目摘要/摘要 发育是非常可重复性的，通常产生相同的器官，大小，形状， 每个个体的结构和功能。健壮性是细胞系统调整和发展的能力 面对随机波动，以及环境和遗传因素，器官的正确大小和形状 变种。在缺乏稳健性的情况下，这些扰动将导致器官大小和 形状。提出的创建健壮性的机制包括负反馈环路、冗余 调节网络，协调细胞行为的细胞间信号，变异性的时空平均， 和机械信令，所有这些都在系统级别运行，并在 包括人类在内的多细胞生物。为了确定健壮性是如何出现的，我们用 器官大小或形状(VOS)的可变性增强，从而破坏稳健性。我们的拟南芥花瓣 (最外层的花器官)系统是唯一适合于这些研究的系统，因为每种植物产生的 超过100个隔膜，允许对单个个体的器官健壮性进行统计分析，这是无法完成的 在大多数其他系统中。我们的目标是将这些vos突变体与创新的定量 生物学方法结合了正在生长的萼片的实时成像，图像处理来量化生长， 计算模型、生物力学测试、分子遗传学和基因组学来阐明机制 产生健壮性。我们假设机械信号和生长的协调可能是 对于器官形状和大小的健壮性尤为重要。(目标1)首先，我们将阐明 时空平均中的机械信号以产生健壮的器官。基于计算 建模时，我们假设细胞的时空平均需要适当的机械信号 生长的可变性，以产生强壮的器官。我们将使用改变机械结构的突变体来验证这一假说 与vos1突变体一起发出信号，从而抑制时空平均。(目标2)第二，我们将 确定使器官启动同步的机制以及它们如何有助于 器官大小。Vos2突变体表现出不同的裂片大小和不规则的裂片原基起始时间。我们会 检验这样一种假设，即不同的器官大小是由于失去器官启动时间的稳健性而产生的 通过检测生物力学和激素信号，这两者都有助于原基的形成。 (目标3)第三，我们将确定器官三个维度的生长协调 有助于增强形状的健壮性。Vos3突变体表现出不同的花冠形状；我们假设这一结果 由于组织层之间的生长协调受到干扰而导致外部萼片的机械弯曲 浮出水面。我们将使用计算模型来预测增长率和机制的差异，这些差异可以 导致机械屈曲，并在Vos3中进行测试。这些目标将共同揭示机制和原则。 产生器官大小和形状的健壮性，这是人类发展的基础。

Project Summary/Abstract Development is remarkably reproducible, generally producing the same organ with invariant size, shape, structure, and function in each individual. Robustness is the ability of cellular systems to adjust and develop the correct size and shape organs in the face of stochastic fluctuations, and environmental and genetic variations. In the absence of robustness, these perturbations would cause large variations in organ size and shape. The mechanisms proposed to create robustness include negative feedback loops, redundancy in regulatory networks, intercellular signaling to coordinate cell behaviors, spatiotemporal averaging of variability, and mechanical signaling, all of which function at the systems level and are repeatedly observed in multicellular organisms including humans. To determine how robustness emerges, we identified mutants with enhanced variability in organ size or shape (vos), thus disrupting robustness. Our Arabidopsis thaliana sepal (outermost floral organ) system is uniquely well suited for these studies because each plant produces more than 100 sepals, allowing statistical analysis of organ robustness in a single individual, which cannot be done in most other systems. Our goal is to use these vos mutants in combination with an innovative quantitative biology approach combining live imaging of growing sepals, image processing to quantify growth, computational modeling, biomechanical tests, molecular genetics, and genomics to elucidate mechanisms generating robustness. We hypothesize that mechanical signaling and coordination of growth may be particularly important for robustness of organ shape and size. (Aim 1) First, we will elucidate the role of mechanical signaling in spatiotemporal averaging to produce robust organs. Based on computational modeling, we hypothesize appropriate mechanical signaling is required for spatiotemporal averaging of cellular growth variability to produce robust organs. We will test this hypothesis using mutants that alter mechanical signaling in conjunction with the vos1 mutant, which inhibits spatiotemporal averaging. (Aim 2) Second, we will determine the mechanisms that synchronize organ initiation and how they contribute to robustness of organ size. vos2 mutants exhibit variable sepal size and irregular timing of sepal primordia initiation. We will test the hypothesis that variable organ sizes result from a loss of robustness in the timing of organ initiation through examining biomechanics and hormone signaling, both of which contribute to primordium initiation. (Aim 3) Third, we will determine how coordination of growth across the three dimensions of the organ contributes to robustness in shape. vos3 mutants exhibit variable sepal shapes; we hypothesize this results from perturbed coordination of growth between tissue layers leading to mechanical buckling of the outer sepal surface. We will use computational modeling to predict differences in growth rate and mechanics that can cause mechanical buckling and test these in vos3. Together, these aims will reveal mechanisms and principles generating robustness of organ size and shape, which underlie human development.