BIOPHYSICAL STUDIES OF CYTOSKELETAL FUNCTION

所提出的工作的长期目标是了解机械 动物细胞的功能和特性。 细胞骨架是一种 细胞内相互作用的细丝， 行为，是注意力的中心。 三个相互重叠 强调研究的互补领域。 第一个问题是， 维持细胞形状，收缩张力， 稠度或粘弹性。 三种细胞骨架的作用 丝系统、微丝、微管和中间体 纤维在确定细胞粘弹性将研究与 使用开发的方法测量细胞变形性， 特别是这个目的。 第二个方面涉及机械 肌营养不良蛋白的功能，这种蛋白质在患有 杜氏肌营养不良症。 有证据表明这种蛋白质 在肌肉的表面膜之间提供了一个机械连接 细胞及其肌动蛋白丝系统，其目的是机械 稳定细胞。 这一假设将得到检验， 测量从正常人培养的肌细胞的变形能力 小鼠和缺乏抗肌萎缩蛋白的小鼠，其为人类提供了模型， 疾病 肌营养不良蛋白功能测定的可能性， 将探讨这些测量方法。 这一分析将有助于指导 利用分子遗传学或分子生物学技术， 细胞生物学方法。 第三个工作领域涉及机械 有助于网骨阿米巴运动的过程 盘状突 这种单细胞生物有利于这些研究 由于可用于删除选定的细胞骨架蛋白的方法 使用分子遗传学方法和关于其 运动和趋化反应的机制。 变形能力 在不同的运动时间， 循环，粘附到基板的作用，和运输的 将测量细胞表面上的颗粒以探测 运动 变形网骨藻的运动与许多 方法与哺乳动物白细胞的方法相似，从而为研究白细胞的生物学行为提供了模型。 后者细胞的功能，这是他们的一个重要组成部分， 有助于免疫反应。

The long range goal of the proposed work is to understand the mechanical functions and properties of animal cells. The cytoskeleton, a system of interacting filaments within the cell which governs its mechanical behavior, is at the center of attention. Three overlapping and mutually complementary areas of study are emphasized. The first concerns the role of the cytoskeleton in maintaining cell shape, contractile tension, and consistency or viscoelasticity. The roles of the three cytoskeletal filament systems, microfilaments, microtubules, and intermediate filaments in determining cellular viscoelasticity will be studied with measurements of cellular deformability using methods developed for specifically this purpose. The second area concerns the mechanical functions of dystrophin, the protein absent from patients afflicted with Duchenne muscular dystrophy. Evidence suggests that this protein provides a mechanical link between the surface membrane of the muscle cell and its actin filament system the purpose of which is the mechanical stabilization of the cell. This hypothesis will be tested with measurements of the deformability of muscle cells cultured from normal mice and mice lacking dystrophin which provide a model for the human disease. The possibility of an assay for dystrophin function based on these measurements will be explored. This assay would help guide efforts to restore dystrophin to cells which lack it using molecular genetic or cell biological methods. The third area of work concerns mechanical processes that contribute to locomotion of the amoeba Dictyostelium discoideum. This single cell organism is favorable for these studies because of the methods available to delete selected cytoskeletal proteins using molecular genetic methods and the extensive data about its mechanisms of locomotion and chemotactic responses. The deformabilities of different regions of cells at different times in their locomotory cycles, the role of adhesion to the substrate, and the transport of particles on the cell surface will measured to probe the mechanics of locomotion. The locomotion of Dictyostelium amoebae is similar in many ways to that of mammalian leukocytes, and so provides a model for a function of the latter cells which is an essential component of their contribution to immune responses.