Class I myosins regulate protrusive forces at the actin-membrane interface

在这个项目中，我们将剖析一类肌球蛋白，结合肌动蛋白的分子马达的作用 纤维通过它们的运动域和质膜通过它们的尾部域， 肌动蛋白介导的细胞形状变化。我们将检验肌球蛋白I运动活动 促进分支肌动蛋白网络在膜变形部位的组装，包括 内吞囊泡、吞噬杯和足状体。拟议的工作将使用两个模型 系统：裂殖酵母，其中肌球蛋白I是胞吞作用所必需的，和鼠巨噬细胞， 其依赖肌球蛋白I进行吞噬作用和细胞迁移。在目标1中，我们将确定如何 肌球蛋白运动活性有助于酵母中的内吞肌动蛋白片组装和内化。 我们将使用遗传学上易处理的酵母系统来表达突变的肌球蛋白， 内源性肌球蛋白基因座，并应用分子计数技术，这是很好地建立 在酵母胞吞系统中，测量肌动蛋白组装的速率。在目标2中，我们将测试 肌球蛋白运动活性在吞噬和细胞内肌动蛋白和膜动力学中作用 迁移这些研究将利用缺乏I类基因的转基因小鼠 我们实验室里就有肌球蛋白在目标3中，我们将确定肌球蛋白膜 相互作用被调节以促进肌动蛋白组装和免疫中的肌球蛋白功能。 反应拟议的工作将阐明驱动肌动蛋白的分子机制， 依赖膜变形。

In this project, we will dissect the roles of class I myosins, molecular motors that bind actin filaments through their motor domains and plasma membrane through their tail domains, in actin-mediated cell shape changes. We will test the hypothesis that myosin I motor activity promotes assembly of branched actin networks at the sites of membrane deformation, including endocytic vesicles, phagocytic cups, and podosomes. The proposed work will use two model systems: fission yeast, where myosin I is required for endocytosis, and murine macrophages, which rely on myosin I for phagocytosis and cell migration. In aim 1, we will determine how myosin motor activity contributes to endocytic actin patch assembly and internalization in yeast. We will use the genetically tractable yeast system to express mutant myosin from the endogenous myosin locus and apply molecule counting techniques, which are well established in the yeast endocytosis system, to measure the rates of actin assembly. In aim 2, we will test the role of myosin motor activity in actin and membrane dynamics during phagocytosis and cell migration. These studies will take advantage of the genetically modified mice lacking class I myosins that are available in our labs. In aim 3, we will determine how myosin-membrane interactions are regulated to contribute to myosin functions in actin assembly and immune response. The proposed work will shed light on the molecular mechanisms driving actin- dependent membrane deformation.