Molecular Mechanisms of Semaphorin/Plexin-mediated Cytoskeletal Reorganization

信号蛋白/丛蛋白介导的细胞骨架重组的分子机制

基本信息

批准号：
8087940
负责人：
JONATHAN R TERMAN
金额：
$ 34.67万
依托单位：
UT SOUTHWESTERN MEDICAL CENTER
依托单位国家：
美国
项目类别：
财政年份：
2011
资助国家：
美国
起止时间：
2011-02-15 至 2016-01-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8087940
关键词：
Actins Addictive Behavior Adult Behavior Binding Biochemical Biochemistry Biological Biological Assay Biological Models Cell Culture Techniques Cell Surface Receptors Cell surface Cells Cellular biology Cues Cultured Cells Cytoskeletal Modeling Cytoskeleton Dendrites Development Diagnosis Drosophila genus Emotions Enzymes Event F-Actin Family Filament Functional disorder Genes Genetic Goals Image In Vitro Injury Invertebrates Learning Length Link Logic Mammals Mass Spectrum Analysis Mediating Microfilaments Modification Molecular Morphology Movement Mutagenesis NADP Nervous system structure Neurons Neurosciences Research Oxidation-Reduction Oxidoreductase Post-Translational Protein Processing Prevention strategy Process Property Proteins Publishing Recovery Regulation Resolution Role Semaphorins Shapes Signal Pathway Signal Transduction Specific qualifier value Structure Synaptic Transmission Testing Therapeutic Time Total Internal Reflection Fluorescent Trauma Vertebral column Walking adhesion process axon growth axon guidance base cell behavior cell motility depolymerization direct application extracellular in vivo member migration nervous system disorder novel plexin polymerization prevent receptor relating to nervous system response structural biology synaptogenesis

项目摘要

DESCRIPTION (provided by applicant): The goals of this project are to characterize a new biological mechanism that has direct application to the regulation of the actin cytoskeleton - the structure underlying neural cell behaviors including morphology, polarity, adhesion, process elongation, motility, navigation, connectivity, and plasticity. In order to change their size, shape, and connectivity, neurons require actin proteins to assemble together into long filaments. Adjusting the length and organization of these actin filaments (F-actin) specifies the direction of movement and enables cells to precisely connect and communicate with one another. A number of extracellular cues have now been identified that control actin dynamics, but we know little of how these signals present outside of cells exert their precise effects within cells. Semaphorins (Semas) are one of the largest families of these guidance cues and they regulate cellular behaviors by eliciting destabilizing effects on F-actin that include a loss of F- actin and the decreased ability to polymerize new F-actin. Importantly, recent breakthroughs have identified cell-surface receptors and intracellular proteins that are essential for Sema-mediated effects on actin but we still know little of the molecular mechanisms that directly regulate F-actin in response to Semas. To identify these molecules and mechanisms we have identified proteins that associate with the Sema receptor Plexin, including a novel family of cytosolic proteins called the MICALs. There is one MICAL gene in invertebrates and three MICAL genes in mammals and they control axon guidance, synaptogenesis, dendritic pruning, and other morphological changes mediated Semas/Plexins. Indeed, our recently published results reveal that MICAL provides a long-sought-after direct link between Semas/Plexins and the modification of the actin cytoskeleton. We find that MICAL directly disassembles F-actin and is both necessary and sufficient for regulating actin dynamics downstream of Semas/Plexins. These new results provide an underlying logic through which Sema- mediated reorganizations of the actin cytoskeleton can be precisely achieved in space and time: through direct Sema-Plexin activation of the novel actin disassembly factor MICAL. Interestingly, MICALs also contain an oxidoreductase (Redox) enzymatic moiety and our results strongly suggest that MICAL utilizes its Redox activity to alter F-actin, implicating for the first time a role for specific Redox signaling events in actin cytoskeletal regulation. Therefore, I hypothesize that MICAL enzymes are a novel family of phylogenetically conserved actin disassembly factors that utilize a previously uncharacterized reversible Redox signaling mechanism to directly regulate actin dynamics. To test this hypothesis, I propose to combine genetics, cell culture, and cell biological approaches using both invertebrate and vertebrate model systems with biochemical, structural, and high-resolution imaging assays utilizing purified MICAL and actin proteins. Understanding how this unusual family of enzymes, the MICALs (which are unlike any proteins that have ever been characterized) causes F-actin to disassemble will reveal new strategies to regulate neural cell biology and behavior. PUBLIC HEALTH RELEVANCE: Our nervous system controls such remarkable abilities as learning, speaking, and walking only because our neurons communicate in highly organized networks. The goal of this proposal is to characterize the biochemical mechanisms that enable neurons to find and connect with one another during development and maintain these proper connections through-out adulthood. Understanding how these neuronal networks are assembled, integrated, and maintained will reveal fundamental mechanisms underlying thought, emotion, and behavior, identify therapeutic strategies for neurological diseases and addictive behaviors, and contribute to healthy recovery following neural trauma.

描述（由申请人提供）：该项目的目标是表征一种新的生物学机制，该机制直接适用于肌动蛋白细胞骨架的调节 - 神经细胞行为的基础结构，包括形态，偏振，粘附，过程伸长，流动性，运动性，导航，连通性和可塑性。为了改变其大小，形状和连通性，神经元需要肌动蛋白蛋白一起组装成长丝。调整这些肌动蛋白丝（F-肌动蛋白）的长度和组织指定运动的方向，并使细胞可以精确地连接和通信。现在已经确定了许多控制肌动蛋白动力学的细胞外提示，但是我们几乎不知道这些信号在细胞之外如何在细胞内发挥其精确效应。信号蛋白（SEMA）是这些指导提示中最大的家族之一，它们通过引起对F-肌动蛋白的稳定作用来调节细胞行为，其中包括F-肌动蛋白的丧失和聚合新的F-肌动蛋白的能力降低。重要的是，最近的突破已经确定了细胞表面受体和细胞内蛋白，这些受体对于SEMA介导的肌动蛋白的作用至关重要，但我们仍然对响应SEMA的直接调节F-肌动蛋白的分子机制几乎不知道。为了鉴定这些分子和机制，我们已经鉴定出与SEMA受体丛蛋白相关的蛋白质，包括一种新型的胞质蛋白家族，称为Micals。无脊椎动物中有一个微分基因，哺乳动物中有三个微基因，它们控制着轴突引导，突触发生，树突修剪和其他形态学变化介导的SEMAS/PLEXINS。确实，我们最近发表的结果表明，Mical提供了SEMAS/PLEXINS与肌动蛋白细胞骨架的修饰之间的长期直接联系。我们发现Mical直接分解F-肌动蛋白，并且对于调节SEMAS/PLEXINS下游的肌动蛋白动力学既需要且足够。这些新的结果提供了一种潜在的逻辑，可以通过该逻辑在时空和时间上精确地实现肌动蛋白细胞骨架的半介导的重组：通过新型肌动蛋白分解因子麦克学因素的直接SEMA-粘蛋白激活。有趣的是，MICALS还包含氧化还原酶（氧化还原）酶促部分，我们的结果强烈表明Mical利用其氧化还原活性来改变F-肌动蛋白，这首次涉及肌动蛋白细胞骨架调节中特定氧化还原信号事件的作用。因此，我假设微分酶是一种新型的系统发育保守的肌动蛋白拆卸因子，它们利用先前未表征的可逆氧化还原信号传导机制直接调节肌动蛋白动力学。为了检验这一假设，我建议使用无脊椎动物和脊椎动物模型系统与生化，结构和高分辨率成像测定法相结合的遗传学，细胞培养和细胞生物学方法，利用纯化的麦克罗和肌动蛋白蛋白。了解这种不寻常的酶家族是如何导致F-肌动蛋白拆卸的Micals（与任何蛋白质不同的蛋白质不同）将揭示调节神经细胞生物学和行为的新策略。公共卫生相关性：我们的神经系统控制着出色的能力，例如学习，说话和行走，只是因为我们的神经元在高度组织的网络中进行通信。该提案的目的是表征生化机制，这些机制使神经元在开发过程中可以找到并相互联系，并在成年期间保持这些适当的联系。了解这些神经元网络如何组装，整合和维护将揭示基本思想，情感和行为的基本机制，确定神经系统疾病和成瘾行为的治疗策略，并在神经创伤后有助于健康康复。