Mechanisms of Formin-Mediated Actin Filament Assembly - Renewal 01 - Resubmission

福尔明介导的肌动蛋白丝组装机制 - 续订 01 - 重新提交

基本信息

批准号：
8985681
负责人：
David R Kovar
金额：
$ 38.66万
依托单位：
UNIVERSITY OF CHICAGO
依托单位国家：
美国
项目类别：
财政年份：
2007
资助国家：
美国
起止时间：
2007-09-01 至 2017-12-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8985681
关键词：
Actin-Binding Protein Actins Amino Acid Sequence Architecture Area Binding Biochemical Biochemistry Biological Biological Assay Cell Polarity Cell physiology Cells Color Complement Complex Congenital Abnormality Crowding Cytoplasm Cytoskeleton Directed Molecular Evolution Drosophila genus Elongation Factor Endocytosis Equilibrium Filament Filopodia Fission Yeast Genetic Goals Grant In Vitro Investigation Ligands Malignant Neoplasms Mediating Microfilaments Molecular Motor Myosin ATPase Play Plus End of the Actin Filament Process Proline Property Proteins Regulation Research Role Saccharomycetales Side Signal Transduction Specificity Structure Techniques Testing Time Total Internal Reflection Fluorescent Travel Work base cell motility follow-up formin-2 in vivo insight microscopic imaging monomer mutant novel polymerization prevent profilin public health relevance response scaffold single molecule vasodilator-stimulated phosphoprotein

项目摘要

DESCRIPTION (provided by applicant): Cells simultaneously assemble functionally diverse actin cytoskeleton filaments with distinct architectures and dynamics to drive fundamental processes such as polarization, endocytosis, motility and division. Multiple actin filament-based structures must self-organize within a single crowded cytoplasm to maintain organization and functional specificity. Numerous actin-binding proteins with different properties regulate actin assembly and organization. Cells remain poised to assemble actin filaments at the right time and place in response to signals because they maintain a large pool of actin monomers bound to the small actin-binding protein profilin. Profilin prevents unwanted spontaneous actin assembly by inhibiting nucleation, so factors are required to rapidly stimulate actin assembly at the right time and place in response to signals. Most new actin filaments are produced by an expanding list of nucleation and elongation factors that establish diverse actin filament architectures required for different processes. Formin utilizes a conceptually novel mechanism to stimulate the assembly of rapidly elongating long-straight filaments that are often pulled by myosin motors to generate contractile forces or to provide polarized tracks and/or scaffolds that establish/maintain cell polarity and filopodia extension. Ena/VASP also promotes the elongation of long-straight filaments for extending filopodia at the leading edge of migrating cells. Conversely, Arp2/3 complex initiates the assembly of short-branched filaments that provide pushing forces. A major unresolved question is to determine how diverse nucleation factors work alone and in combination to assemble profilin-actin into functionally diverse actin filaments within a crowded common cytoplasm. Our hypothesis is that actin monomers are limiting, and therefore competition for profilin-actin by nucleation factors plays a critical role in maintaininga balance between different actin filament-based structures within a crowded cytoplasm. Profilin not only facilitates formin- and Ena/VASP-mediated actin filament elongation, but also allows formin to successfully compete with an excess of Arp2/3 complex for actin monomers. Our research goals are to determine the essential cellular role(s) of profilin, and follow up on progress made in our previous grant to investigate the precise mechanisms by which formins utilize profilin-actin for rapid actin filament elongation (Aim I). We are also expanding into the high impact area of investigating how formin competes with Arp2/3 complex for profilin-actin to drive different processes (Aim II), and how formin competes and/or cooperates with Ena/VASP to assemble actin filaments for filopodia (Aim III).

描述（由申请人提供）：细胞同时组装具有不同结构和动力学的功能多样的肌动蛋白细胞骨架丝，以驱动极化、内吞作用、运动和分裂等基本过程。多个基于肌动蛋白丝的结构必须在单个拥挤的细胞质内自组织，以维持组织和功能特异性。许多具有不同特性的肌动蛋白结合蛋白调节肌动蛋白的组装和组织。细胞保持准备在正确的时间和地点组装肌动蛋白丝以响应信号，因为它们保持大量肌动蛋白单体与小的肌动蛋白结合蛋白分布蛋白结合。 Profilin 通过抑制成核来防止不需要的自发肌动蛋白组装，因此需要一些因子来响应信号在正确的时间和地点快速刺激肌动蛋白组装。大多数新的肌动蛋白丝是通过不断扩大的成核和伸长因子产生的，这些因素建立了不同过程所需的不同肌动蛋白丝结构。 Formin 利用概念上新颖的机制来刺激快速伸长的长直丝的组装，这些丝通常由肌球蛋白马达拉动以产生收缩力或提供极化轨道和/或支架来建立/维持细胞极性和丝状伪足延伸。 Ena/VASP 还促进长直丝的伸长，以延长迁移细胞前缘的丝状伪足。相反，Arp2/3 复合体启动提供推力的短支化丝的组装。一个未解决的主要问题是确定不同的成核因子如何单独和组合发挥作用，在拥挤的共同细胞质内将肌动蛋白-肌动蛋白组装成功能多样的肌动蛋白丝。我们的假设是肌动蛋白单体是有限的，因此成核因子对肌动蛋白-肌动蛋白的竞争在维持拥挤的细胞质内不同肌动蛋白丝结构之间的平衡方面发挥着关键作用。 Profilin 不仅促进 formin 和 Ena/VASP 介导的肌动蛋白丝伸长，而且还允许 formin 成功与过量的 Arp2/3 复合物竞争肌动蛋白单体。我们的研究目标是确定 profilin 的重要细胞作用，并跟进我们之前的资助所取得的进展，以研究福明利用 profilin-肌动蛋白实现肌动蛋白丝快速伸长的精确机制（目标 I）。我们还正在扩展到研究福明如何与 Arp2/3 复合物竞争肌动蛋白-肌动蛋白以驱动不同过程的高影响领域（目标 II），以及福明如何与 Ena/VASP 竞争和/或合作来组装丝状伪足的肌动蛋白丝（目标三）。