Deciphering the Mechanisms and Cellular Roles of Monomer-Driven Actin Dynamics

项目摘要 为了分裂、移动和交流，细胞依赖于动态肌动蛋白细胞骨架，该动态肌动蛋白细胞骨架可以快速组装并 变化这是通过肌动蛋白单体聚合成细丝来实现的， 网络，并将这些网络分解回单体。细胞保持大量单体储备 以满足肌动蛋白网络组装的需要。由于单体池的大小， 被认为是同质的。然而，我们和其他人最近的工作揭示了不同的亚群， 这些单体可以驱动和改变肌动蛋白动力学，从而深刻影响细胞行为。这些 新的发现告诉我们，单体聚合的规律比以前复杂得多 想的解决这一严重的知识差距在一个最基本的方面的细胞骨架生物学 对理解肌动蛋白在细胞中的功能至关重要。它也可能最终揭示为什么单体中的缺陷 调节与神经变性、炎性疾病、心脏病和癌症有关。 我们目前对肌动蛋白单体行为的认识大多来自于溶液生物化学。但这些 这类实验不能再现在细胞中看到的复杂单体驱动的肌动蛋白动力学。因此，我们认为， 我们正在设计将生物化学原理与细胞成像相结合的策略，以揭示单体肌动蛋白 调节活细胞中的细胞骨架。这包括以微摩尔精度控制蛋白质水平， 定量图像分析，以提取速率常数和浓度，并采用计算模型 来揭示细胞几何结构如何影响肌动蛋白动力学。此外，我们正在开发新的工具来描述 并从超分辨率图像中量化肌动蛋白超微结构。我们将利用这些创新方法， 解决以下关于单体驱动的肌动蛋白动力学的基本知识差距：1）单体如何 控制复杂肌动蛋白网络的动力学，2）细胞几何形状如何有助于单体调节肌动蛋白 动力学，和3）单体在细胞过程调节中的新作用。

Project Summary To divide, move, and communicate, cells rely on a dynamic actin cytoskeleton that can rapidly assemble and change. This is achieved by the polymerization of actin monomers into filaments, the construction of filament networks, and the disassembly of these networks back into monomers. Cells maintain a large monomer reserve to meet the demands of actin network assembly. Because of its size, the monomer pool was traditionally considered to be homogeneous. However, recent work by us and others has revealed distinct subgroups of monomers that can drive and modify actin dynamics in ways that profoundly influence cell behavior. These discoveries have shown us that the rules of monomer polymerization are much more complex than previously thought. Addressing this severe knowledge gap in one of the most fundamental aspects of cytoskeletal biology is paramount to understanding how actin functions in cells. It may also finally reveal why defects in monomer regulation are associated with neurodegeneration, inflammatory disorders, cardiac disease and cancer. Most of our current knowledge about actin monomer behavior comes from solution biochemistry. However, these types of experiments cannot reproduce the complex monomer-driven actin dynamics seen in cells. Therefore, we are devising strategies that merge biochemical principles with cellular imaging to reveal how monomeric actin regulates the cytoskeleton in living cells. This includes controlling protein levels with micromolar precision, using quantitative image analysis to extract rate constants and concentrations, and employing computational models to reveal how cellular geometry influences actin dynamics. Additionally, we are developing new tools to describe and quantify actin ultrastructure from super-resolution images. We will use these innovative approaches to address the following fundamental knowledge gaps about monomer-driven actin dynamics: 1) How monomers control the dynamics of complex actin networks, 2) How cell geometry contributes to monomer-regulated actin dynamics, and 3) Novel roles for monomers in the regulation of cellular processes.