Fibronectin-dependent mechanisms governing the assembly of a definitive extracellular matrix

项目摘要 拟议的工作旨在揭示新的机制，管理组装的细胞外 基质（ECM）蛋白纤连蛋白（FN）及其在指导其他ECM蛋白组装以形成一种基质中的作用。 最终矩阵因为确定性基质是关键物理、化学和机械性能的组成部分， 调节组织结构和功能，了解协调FN组装的机制， 与I型胶原蛋白和其他ECM蛋白的结合是至关重要的。基质组装中的分子缺陷与 纤维化，其中由于FN、胶原蛋白I和其他胶原蛋白的异常产生而导致紊乱的ECM纤维积聚， 基质蛋白沿着纤维化、骨骼异常、肿瘤发生和其他ECM相关疾病 影响着地球仪上数以百万计的人，但在大多数情况下，ECM的缺陷知之甚少， 很多方面，仍然无法治愈。拟议的工作将检验该组织和 细胞周围FN基质的不溶性控制并指导组织合适的永久基质的组装， FN基质的扰动破坏组织和细胞功能，导致疾病。我们有个将军 了解FN基质组装的主要步骤，但控制FN原纤维的具体机制 组织、原纤维稳定性或FN如何引导胶原组装尚未阐明。拟议 目标将解决这些机制，建立在我们已经建立的基础上，与我们的前 工作我们将使用我们成熟的基质组装系统来分析FN原纤维的形成及其对细胞的影响。 I型胶原蛋白组装的贡献，以确定蛋白质相互作用，这是至关重要的指导 最终矩阵组装。目的1的目标是确定可逆FN-FN转化的机制 相互作用形成稳定的不溶性原纤维。我们将测试一个新的假设，即肝素/硫酸乙酰肝素作为一种 分子开关通过结合FN和诱导构象变化，促进强蛋白质-蛋白质 交互.目的2将阐明FN基质作为胶原纤维形成的模板的假设， 为胶原蛋白加工酶的定位和活化提供平台。Aim 3将连接FN 组装与细胞分化。使用一种新发现的人类FN突变， 发育不良，我们将确定由这种突变引起的基质组装缺陷，并将应用微团 软骨形成模型系统，以了解突变FN基质对细胞分化的影响。我们的工作 将填补我们对大会关键步骤的管理机制的理解方面的关键知识空白。 一个明确的矩阵，并将建议的途径，病理过程或突变可能导致异常 矩阵组织或积累。这项工作将为操纵ECM的策略产生新的想法 组装以治疗或控制纤维化和其他ECM相关疾病，并可能导致基于ECM的 治疗，以改善疾病的结果。

PROJECT SUMMARY The proposed work seeks to uncover novel mechanisms governing the assembly of the extracellular matrix (ECM) protein fibronectin (FN) and its role in directing assembly of other ECM proteins to form a definitive matrix. Because the definitive matrix is integral to key physical, chemical, and mechanical properties that regulate tissue structures and functions, understanding mechanisms that coordinate the assembly of FN with type I collagen and other ECM proteins is crucial. Molecular defects in matrix assembly are implicated in fibrosis in which disordered ECM fibers accumulate due to abnormal production of FN, collagen I, and other matrix proteins. Along with fibrosis, skeletal abnormalities, tumorigenesis, and other ECM-related diseases affect millions of people around the globe yet in most cases the ECM defects are poorly understood and, in many ways, still largely untreatable. The proposed work will test the hypothesis that the organization and insolubility of the pericellular FN matrix control and direct the assembly of a tissue-appropriate definitive matrix, and that perturbation of the FN matrix disrupts tissue and cell functions leading to disease. We have a general understanding of the main steps of FN matrix assembly, but specific mechanisms governing FN fibril organization, fibril stability, or how FN guides assembly of collagens have yet to be elucidated. The proposed aims will address these mechanisms, building on the foundation that we have established with our previous work. We will use our proven matrix assembly systems to analyze the formation of FN fibrils and their contributions to type I collagen assembly to determine the protein interactions that are critical for directing definitive matrix assembly. The goal of Aim 1 is to determine the mechanism that converts reversible FN-FN interactions into stable insoluble fibrils. We will test a new hypothesis that heparin/heparan sulfate acts as a molecular switch by binding to FN and inducing conformational changes that promote strong protein-protein interactions. Aim 2 will address the hypothesis that FN matrix acts as a template for collagen fibrillogenesis by providing a platform for the localization and activation of collagen processing enzymes. Aim 3 will link FN assembly with cell differentiation. Using a newly discovered human FN mutation potentially linked to a skeletal dysplasia, we will determine the matrix assembly defect caused by this mutation and will apply the micromass chondrogenesis model system to understand the effects of mutant FN matrix on cell differentiation. Our work will fill critical knowledge gaps in our understanding of the mechanisms governing key steps in the assembly of a definitive matrix, and will suggest routes by which pathological processes or mutations can cause abnormal matrix organization or accumulation. This work will generate new ideas for strategies to manipulate ECM assembly in order to treat or control fibrosis and other ECM-related diseases and may lead to ECM-based treatments to improve disease outcomes.