Cytoskeleton-based regulation of microtubule motors in intracellular transport.

细胞的形态和机械性能由细胞骨架（一组生物聚合物细丝）维持。细胞骨架是高度动态的，不断重塑，以允许细胞分裂和运动等基本功能所需的细胞形状变化。同时，细胞骨架丝作为运动蛋白携带囊泡物质到细胞内不同位置的沿着轨迹。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米的长细胞。这些双重结构和运输作用对细胞骨架提出了竞争性要求-同时作为固体来维持细胞形态，并作为流体来允许囊泡货物和细胞器通过细胞空间的有效运动。为了满足各种各样的需求，细胞骨架丝不断地伸展和去伸展，交联蛋白质在丝之间和细胞膜上形成动态键，允许在不同的时间和长度尺度上调节机械性能。细胞骨架不是简单地充当马达蛋白的被动轨道，而是通过其网络结构、翻译后修饰和细胞骨架相关蛋白主动调节其活性。这些细胞骨架线索引导细胞内交通，以维持蛋白质、mRNA、细胞器和信号分子的适当空间和时间定位。该发现计划旨在（1）识别和表征允许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马达蛋白功能以实现细胞内货物的定向运输。在拟议的发现计划中，我们将开发先进的光学捕获技术，以执行高分辨率的测量频率依赖的粘弹性的细胞环境，并检查扰动的动态力学响应的细胞骨架交联剂的动力学的影响。此外，我们将使用新的体外重建试验，以检查孤立的内源性货物对天然细胞骨架网络的运动。通过该计划，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的专家。拟议的研究将导致对细胞骨架如何动态调整其机械响应和调节马达蛋白以指导细胞内运输的新见解，从而提高我们对细胞生物学的基本理解，以及设计由生物马达蛋白驱动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.