The Role of Cap Z in Sarcomere Organization and Function in Drosophila

调节肌动蛋白组装的机制负责赋予细胞形式和功能。肌动蛋白是一种蛋白质，它有助于细胞内的支撑结构和引起收缩的机制，因此它对肌肉细胞的存在和功能至关重要。本研究旨在探讨肌肉细胞的形成及其调控机制。从技术上讲，在高等生物的肌肉细胞上进行这项研究是不可能的，因为基因操作的能力是不可能的。PI使用果蝇肌肉发育作为模型系统进行分析。该系统是真核细胞遗传分析的种子系统，可以很容易地用于涉及遗传操作的研究。由于肌肉细胞的组织结构在真核生物中是高度保守的，预计该系统的结果可以很容易地推断到其他真核细胞。PI感兴趣的是肌动蛋白聚合是如何被控制的，以及在真核生物中许多不同类型的细胞中如何形成和定位不同的含有肌动蛋白的结构。特别令人感兴趣的是肌肉节的组装过程。肌动蛋白丝的排列高度规则，其位置和组织对肌肉功能至关重要。为了了解这种规则的肌动蛋白丝阵列是如何产生的，PI正在研究肌动蛋白结合蛋白Cap Z。Cap Z是一种异二聚体蛋白（α和β亚基），在体外结合并阻断肌动蛋白丝的有刺（快速生长）末端的聚合。它位于脊椎动物肌肉的z线，肌动蛋白丝的倒钩端终止并锚定在这里。Cap Z的体外特性及其在肌肉中的定位表明，它是控制肌动蛋白聚合和/或锚定肌动蛋白细丝的关键成分。然而，它在体内的功能还缺乏明确的证据。PI将获得关于肌肉肌动蛋白丝组织是如何产生的直接信息，特别是Cap Z的作用，通过在果蝇中编码Cap Z亚基（β）的基因中进行突变。果蝇是研究肌肉功能的一个有吸引力的模型系统，因为它的肌肉组织与脊椎动物的肌肉相似，但它可以用脊椎动物很难或不可能的遗传技术来操纵。PI将研究Cap Z β突变果蝇的肌肉发育、组织和功能，并研究Cap Z在携带其他肌节成分突变的果蝇中的分布。通过这些研究，PI将确定肌肉的不同蛋白质如何相互作用以产生其结构。这些研究应该适用于各种各样的生物体

Miller 9419106 The mechanisms which regulate actin assembly are responsible for giving both form and function to cells. Actin is a protein which contributes to support structures within the cell and to mechansims which cause contraction, and consequently it is central to the existence and function of muscle cells. This proposal investigates the formation of, and regulatory mechanisms in, muscle cells. It would be technically impossible to conduct this studies on muscle cells from higher organisms because the ability for genetic manipulation is not possible. The PI uses Drosophila muscle development as a model system for the analysis. This system is the seminal system for genetic analysis in eukaryotic cells and can easily be employed for studies involving genetic manipulation. Since muscle cells organization is highly conserved among eukaryotics results from this system are anticipated to be easily extrapolated to other eukaryotic cells %%% The PI is interested how actin polymerization is controlled and how different actin-containing structures are formed and positioned in many different types of cells in eukaryotic organisms. Of particular interest is the process of muscle sarcomere assembly. A highly regular array of actin filaments is present, the location and organization of which is essential to muscle function. To understand how this regular array of actin filaments is generated, the PI is studying the actin binding protein, Cap Z. Cap Z is a heterodimeric protein (alpha and beta subunits) that binds to and blocks polymerization at the barbed (fast-growing) end of an actin filament in vitro. It is located at the Z-line of muscle in vertebrates, where the barbed end of actin filaments terminate and are anchored. Cap Z's properties in vitro and its localization in muscle suggest that it is a key component in controlling actin polymerization and/or anchoring actin filaments. However, definitive evidence for its function in vivo is lacking. The PI will obtain direct inform ation about how the actin filament organization of muscle is generated and in particular, the role of Cap Z, by making mutations in the gene that encodes one of the Cap Z subunits (beta) in the fruit fly, Drosophila. Drosophila is an attractive model system for studies on muscle function because its muscles are organized similarly to vertebrate muscles, yet it can manipulated using genetic techniques that are difficult or impossible in vertebrates. The PI will study the development, organization and function of muscles in Cap Z beta mutant flies and study Cap Z's distribution in flies that carry mutations in other sarcomere components. Through these studies the PI will determine how different proteins of the muscle interact to generate its structure. These studies should be applicable to a wide variety of organisms ***