BIOPHYSICAL STUDIES OF CYTOSKELETAL FUNCTION

拟议工作的长期目标是了解机械 动物细胞的功能和特性。 细胞骨架是一个系统 细胞内相互作用的细丝控制其机械性能 行为，成为人们关注的焦点。 三者重叠又相互 强调互补的研究领域。 首先是关于角色 细胞骨架在维持细胞形状、收缩张力和 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 将研究确定细胞粘弹性的细丝 使用开发的方法测量细胞变形性 特别是这个目的。 第二个领域涉及机械 抗肌营养不良蛋白的功能，这种蛋白在患有肌营养不良症的患者中缺失 杜氏肌营养不良症。 有证据表明这种蛋白质 在肌肉表面膜之间提供机械连接 细胞及其肌动蛋白丝系统，其目的是机械作用 细胞的稳定。 该假设将被检验 测量正常培养的肌肉细胞的变形能力 小鼠和缺乏肌营养不良蛋白的小鼠为人类提供了模型 疾病。 基于抗肌营养不良蛋白功能测定的可能性 将探讨这些测量方法。 该分析将有助于指导工作 使用分子遗传学或 细胞生物学方法。 第三个工作领域涉及机械 有助于阿米巴网网柄菌运动的过程 盘状体。 这种单细胞生物有利于这些研究 因为可用于删除选定的细胞骨架蛋白的方法 利用分子遗传学方法和有关其的大量数据 运动和趋化反应的机制。 变形能力 不同区域的细胞在不同时间的运动 循环、粘附到基材上的作用以及传输 将测量细胞表面的颗粒以探究其机理 运动。 阿米巴盘基网柄菌的运动在许多方面都相似 哺乳动物白细胞的方法，因此提供了一个模型 后者细胞的功能是其重要组成部分 对免疫反应的贡献。

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.