BIOPHYSICAL STUDIES OF CYTOSKELETAL FUNCTION

所提议的工作的长期目标是理解机械 动物细胞的功能和特性。细胞骨架，一种 细胞内相互作用的细丝，它控制着它的机械 行为，是人们关注的中心。三个相互重叠、相互促进 强调研究的互补性领域。第一个问题与角色有关 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 细丝系统、微丝、微管和中间体 确定细胞粘弹性的细丝将用 使用开发的方法测量细胞变形性 具体地说就是为了这个目的。第二个领域涉及机械设备 抗肌营养不良蛋白的功能，这是一种患者缺乏的蛋白质 杜兴氏肌营养不良症。有证据表明，这种蛋白质 在肌肉的表面膜之间提供机械连接 细胞及其肌动蛋白细丝系统，其目的是机械地 细胞的稳定性。这一假设将通过以下方式进行检验 培养的正常人肌细胞变形性的测定 为人类提供模型的小鼠和缺乏肌营养不良蛋白的小鼠 疾病。抗肌营养不良蛋白功能检测的可能性 我们将探索这些测量方法。这一化验将有助于指导努力 使用分子遗传学或分子遗传学方法将营养不良蛋白恢复到缺乏它的细胞中 细胞生物学方法。第三个工作领域与机械有关 蠕形阿米巴的运动过程 盘状骨。这种单细胞有机体对这些研究有利。 因为现有的方法可以删除选定的细胞骨架蛋白 利用分子遗传学方法和关于其的大量数据 运动和趋化反应的机制。变形能力 在细胞运动的不同时间的不同区域 循环，粘着到底物的作用，以及 细胞表面的颗粒将被测量以探索 移动。网鞭毛虫的运动在许多方面都是相似的 与哺乳动物白细胞的方式相似，因此提供了一个模型 后一种细胞的功能，这是其重要组成部分 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.