Facilitated transport of actin monomer and cytoskeletal remodeling

所有细胞通过不断分解和重建其内部支架（称为细胞骨架）来移动和改变形状。 关于细胞如何去除和替换细胞骨架碎片，人们已经了解很多。 然而，电池面临的一个根本挑战是如何回收拆卸下来的碎片。 该项目的目标是了解细胞如何将新拆卸的部件移动到新的地方，在这些地方它们需要足够快的速度来改变形状以响应外部信号。 这项工作将揭示细胞如何能够将自己分开，将分解的碎片移动到正确的位置，并在每次移动时将自己重新组合在一起。 这项工作很重要，因为它将揭示整个细胞内部动态重组的基本原理。 了解这些原理对于学习如何协调细胞骨架重塑至关重要，这些知识对于各种应用都至关重要。更广泛影响的活动将包括推广当地科学博物馆，以及帮助在西北地区建立定量生物学社区。肌动蛋白细胞骨架的动态控制对于运动、分裂和极化等过程至关重要。尽管数十年的研究已经确定了控制在细胞前端添加单体和在后端去除单体的机制，但细胞如何将单体从网络后部（单体被移除的地方）运输到网络前部（单体被添加的地方）尚不清楚。 这种运输过程对于细胞稳态至关重要，并且默认为扩散过程，因为它快速且难以测量。 PI 首次直接测量了正向单体传输。 从他们的测量中可以清楚地看出，向前的单体转运比扩散更快，并且依赖于肌球蛋白 II 的收缩。本研究的目的是确定使肌动蛋白前向运输快于扩散的机制，并确定肌球蛋白 II 收缩在驱动和指导前向运输以重塑细胞骨架中的作用。 这些目标将通过结合生物物理测定、分子生物学、光子学、单分子成像和数学/质量传递分析来实现。 该项目预计将确定长距离运输机制，其中扩散速度太慢，并且由于预期运输目的地的空间和时间快速变化而不太可能出现直接电机耦合。

All cells move and change shape by continuously taking apart and rebuilding their internal scaffolding, called a cytoskeleton. A great deal is known about how cells remove and replace cytoskeletal pieces. However, a fundamental challenge for the cell is how to recycle the disassembled pieces. A goal of this project is to understand how cells move the newly disassembled parts to new places where they need to be fast enough to change shape in response to external signals. This work will reveal how cells are able to pull themselves apart, move the disassembled pieces to the right place, and put themselves back together every time they move. The work is important because it will reveal basic principals of dynamic reorganization of the entire cell interior. Understanding these principals is essential to learning how to coordinate cytoskeletal remodeling, knowledge that is critical for a variety of applications. Broader Impact activities will include outreach to a local science museum along with helping to build a quantitative biology community in the northwest.Dynamic control of the actin cytoskeleton is fundamental to processes such as motility, division, and polarization. Although decades of research have defined the mechanisms that control the addition of monomers at the front of the cell and removal of monomers at the back, how the cell transports monomer from the back of the network, where it is removed, to the front of the network, where it is added is unknown. This transport process is essential to cell homeostasis, and it is tacitly assumed to be diffusion because it is fast and difficult to measure. The PIs have for the first time directly measured forward monomer transport. From their measurements it is clear that forward monomer transport is faster than diffusion and dependent upon myosin II contraction. The objectives of this study are to identify the mechanism that makes forward transport of actin faster than diffusion and to define the role of myosin II contraction in driving and directing forward transport to remodel the cytoskeleton. These objectives will be achieved by combining biophysical assays, molecular biology, photonics, single molecule imaging, and mathematical/mass transport analysis. This project is expected to identify long-distance transport mechanisms where diffusion is too slow and direct motor coupling is unlikely because of rapid spatial and temporal changes of the intended transport destination.