Actin Assembly in Non-Motile Cells

肌动蛋白结构对于多细胞生物中许多细胞类型之间的功能和结构差异至关重要。在不同的细胞类型中产生和维持不同的肌动蛋白结构的重要活动尚不清楚。本项目将研究对这些结构的组装至关重要的蛋白质和活性。以果蝇为模型系统，研究了在刚毛细胞中肌动蛋白组装成细丝束的控制。成人的感觉刚毛依赖于肌动蛋白束，在适当的时间和适当的位置组装，以形成其特殊的形状。肌动蛋白组装的调节因子封盖蛋白的功能突变丧失，导致肌动蛋白束，因此，鬃毛形状缺陷。在帽蛋白突变的动物中，当在束组装中与帽蛋白一起工作的其他肌动蛋白调节因子的数量发生轻微改变时，可以观察到肌动蛋白组织的显著变化。因此，帽蛋白突变动物为肌动蛋白调节因子之间的相互作用提供了一个敏感的分析系统。为了完成这些实验，不同的肌动蛋白调节蛋白的数量将通过编码它们的基因突变或转基因来改变，从而增加致敏动物的拷贝数。将分析固定样品和活体样品中肌动蛋白束的组织和组装。所有真核细胞都依赖肌动蛋白结构生存和执行特殊功能。由于肌动蛋白结构及其蛋白质成分在物种间是保守的，因此这些研究的结果将具有普遍的适用性。这项工作还将通过培养本科生、研究生和博士后在科学实践方面产生广泛的影响。此外，这些研究将产生转基因和突变动物的集合，这对对肌动蛋白和不同细胞特化发展感兴趣的细胞生物学家有广泛的用处。

Actin structures are critically important for functional and structural differences among the many cell types of multicellular organisms. The activities important for generation and maintenance of the different actin structures in different cell types are not well understood. This project will investigate the proteins and activities important for assembly of some of these structures. Using Drosophila as a model system, control of actin assembly into filament bundles will be studied in bristle cells. The adult sensory bristle relies on actin bundles, assembled at the proper time and proper place, for its specialized shape. Loss of function mutations in capping protein, a regulator of actin assembly, lead to actin bundle and, therefore, bristle shape defects. When amounts of other actin regulators that work with capping protein in bundle assembly are even slightly altered in capping protein mutant animals, striking changes in actin organization are observed. Thus, capping protein mutant animals provide a sensitive assay system for interactions among actin regulators. To accomplish these experiments, the amounts of different actin regulatory proteins will be altered using mutations in the genes that encode them or transgenes that increase copy number in sensitized [capping protein mutant] animals. The organization and assembly of actin bundles in fixed and live samples will be analyzed. All eukaryotic cells rely on actin structures to live and perform specialized functions. Because actin structures and their protein constituents are conserved across species, the results obtained from these studies will be generally applicable. This work will also have broad impact through training of undergraduates, graduate students, and post-doctoral fellows in the practice of science. In addition, these studies will generate collections of transgenic and mutant animals that are of use to a broad array of cell biologists interested in actin and in the development of different cellular specializations.