Cytoskeleton-based regulation of microtubule motors in intracellular transport.

细胞的形态和机械性能由细胞骨架维持，细胞骨架是一组生物多聚丝。细胞骨架是高度动态的，不断地重塑，以允许细胞形状的变化，这是细胞分裂和运动等基本功能所需的。与此同时，细胞骨架细丝作为马达蛋白携带囊泡货物到达细胞内不同位置的轨迹。定向运输是至关重要的，特别是对于像人类神经元这样可以延伸到1米长的长细胞来说。这些双重的结构和运输角色对细胞骨架提出了相互竞争的要求--既要作为固体来维持细胞形态，又要作为流体来允许囊泡货物和细胞器在细胞空间中有效地移动。为了满足多样化的需求，细胞骨架细丝不断地聚合和解聚，交联蛋白在细丝和细胞膜之间形成动态键，允许机械性能在不同的时间和长度尺度上进行调节。**细胞骨架不只是作为马达蛋白的被动轨迹，而是通过其网络结构、翻译后修饰和细胞骨架相关蛋白来主动调节它们的活性。这些细胞骨架信号指导细胞内的交通，以维持蛋白质、信使核糖核酸、细胞器和信号分子的适当时空定位。**本探索计划寻求(1)识别和描述使细胞骨架动态适应细胞机械特性的分子机制，以及(2)了解细胞骨架如何调节运动蛋白功能以实现细胞内货物的定向运输。在拟议的探索计划中，我们将开发先进的光学捕获技术来对细胞环境的频率相关粘弹性性质进行高分辨率测量，并研究细胞骨架交联剂的动力学扰动对动态机械响应的影响。此外，我们将使用新的体外重建试验来检测分离的内源性货物在天然细胞骨架网络上的运动性。通过这个项目，两名博士生和两名本科生将成为生物物理学、细胞生物学和分析技术方面的专家。**拟议的研究将对细胞骨架如何动态调整其机械响应并调节马达蛋白以指导细胞内运输产生新的见解，从而促进我们对细胞生物学的基本理解，以及设计由生物马达蛋白提供动力的工程纳米级设备的能力。

The morphology and mechanical properties of the cell are maintained by the cytoskeleton, a set of biopolymeric filaments. The cytoskeleton is highly dynamic, constantly remodeling to allow changes in cell shape required for essential functions like cell division and motility. At the same time, cytoskeletal filaments serve as tracks along which motor proteins carry vesicular cargoes to different locations in the cell. Directed transport is critical, particularly for long cells like neurons that can extend up to 1 m in humans. These dual structural and trafficking roles place competing demands on the cytoskeleton - to simultaneously act as a solid to maintain cell morphology, and as a fluid to allow efficient movement of vesicular cargoes and organelles through the cellular space. To meet a diverse array of demands, cytoskeletal filaments continually polymerize and depolymerize and crosslinking proteins form dynamic bonds between filaments and to the cell membrane, allowing mechanical properties to be tuned across various time and length scales.**The cytoskeleton does not simply act as a passive track for motor proteins, instead it actively modulates their activity through its network architecture, post-translational modifications, and cytoskeletal-associated proteins. These cytoskeletal cues direct intracellular traffic to maintain the proper spatial and temporal localization of proteins, mRNA, organelles, and signaling molecules.**This Discovery program seeks to (1) identify and characterize the molecular mechanisms that allow the cytoskeleton to dynamically adapt the cell's mechanical properties, and (2) understand how the cytoskeleton modulates motor protein function to achieve the directed transport of intracellular cargoes. In the proposed Discovery program, we will develop advanced optical trapping techniques to perform high-resolution measurements of the frequency-dependent viscoelastic properties of the cellular environment, and examine the effect of perturbing the kinetics of cytoskeletal crosslinkers on the dynamic mechanical response. In addition, we will use novel in vitro reconstitution assays to examine the motility of isolated endogenous cargoes on native cytoskeletal networks. Through this program, two PhD students and two undergraduate students will become experts in biophysical, cell biological, and analytical techniques.**The proposed studies will result in novel insights into how the cytoskeleton dynamically tunes its mechanical response and regulates motor proteins to direct intracellular transport, leading to advances in our fundamental understanding of cell biology, and the ability to design engineered nano-scale devices powered by biological motor proteins.