EXTRACELLULAR MATRIX ASSEMBLY OF FIBRONECTIN

细胞外基质的组装和降解是一个动态过程 发生在伤口愈合、胚胎发育和转移过程中。 纤维连接蛋白以可溶二聚体的形式在高浓度下循环。 分子存在于血浆和各种其他体液中，并存在于 细胞外纤维网络中不可溶的多聚体形式 结缔组织、肉芽组织、基底膜和 许多胚胎结构。这种多聚体形式的纤维连接蛋白是 被认为是分子的主要功能形式，调节 与伤口修复相关的各种黏附和迁移事件 迁移、胚胎发育和新生血管。因此， 了解纤维连接蛋白组装的基本过程 细胞外基质对我们了解细胞如何 在这些粘合和迁移事件中与基质进行交互。 转化的细胞在它们的相互作用中表现出各种变化 与细胞外基质的粘附性，包括减少粘附性和减少 含有纤维粘连蛋白的细胞外基质的组装。更改后的 纤维连接蛋白的沉积也与动脉粥样硬化有关。 和纤维化症。因此，了解细胞如何将纤维连接蛋白组装成 细胞外基质也将使我们深入了解 改变纤维连接蛋白基质的组装，以适应各种病理过程。 这项建议的主要目的是阐明所涉及的机制。 在可溶性纤维连接蛋白的聚合和随后的组装中 细胞外基质。纤维连接蛋白在细胞外的沉积 基质是一个由细胞介导的过程，由结合 细胞表面特定部位的可溶性纤维连接蛋白。这个首字母 纤维连接蛋白与细胞表面的结合是由氨基末端介导的 纤维连接蛋白70 kDa区域。在可溶物结合之后 纤维连接蛋白到细胞表面，纤维连接蛋白-纤维连接蛋白相互作用是 参与纤维连接蛋白在二硫键稳定的细胞内的积累 聚集在细胞外基质中。这个项目的目标是 为了确定纤维连接蛋白的结构特征，这些结构特征对 纤维连接蛋白基质组装，并确定特定区域如何 纤维连接蛋白参与细胞介导性聚合 纤维连接蛋白进入细胞外基质。这些研究将使用 变异重组纤维连接蛋白分子研究哪些区域 纤维连接蛋白是基质组装所必需的，它们的作用是什么？ 各地区在这一过程中扮演着重要角色。先前的数据表明，这些序列 从头开始建立母体成核位所必需的 组装不同于对聚合很重要的序列 纤维粘连蛋白进入预制基质。这里要检验的假设是 格兰特认为纤维连接蛋白的第一个III型模块和整合素- 纤维连接蛋白的第10个III型模块中的结合位点是必需的 从头开始建立基质组装点，一旦这些 位点建立，缺乏这些序列的外源纤维连接蛋白可以 组装成矩阵。

Assembly and degradation of extracellular matrices are dynamic processes that occur during wound healing, embryogenesis, and metastasis. Fibronectin circulates at a high concentration as a soluble dimeric molecule in plasma and various other body fluids, and exists in an insoluble, multimeric form in the fibrillar network in the extracellular matrix of connective tissue, granulation tissue, basement membranes, and many embryonic structures. This multimeric form of fibronectin is thought to be the primary functional form of the molecule, mediating various adhesive and migratory events associated with wound repair, cell migration, embryogenesis, and neovascularization. Therefore, understanding the fundamental process of how fibronectin is assembled into the extracellular matrix is essential to our knowledge of how cells interact with the matrix during these adhesive and migratory events. Transformed cells exhibit a variety of alterations in their interactions with the extracellular matrix, including reduced adherence, and reduced assembly of fibronectin- containing extracellular matrices. Altered deposition of fibronectin has also been associated with atherosclerosis and fibrosis. Thus, understanding how cells assemble fibronectin into the extracellular matrix will also yield insights into the importance of altered fibronectin matrix assembly to various pathological processes. The broad aim of this proposal is to elucidate the mechanisms involved in the polymerization and subsequent assembly of soluble fibronectin into the extracellular matrix. Deposition of fibronectin in the extracellular matrix is a cell-mediated process that is initiated by the binding of soluble fibronectin to specific sites on the cell surface. This initial binding of fibronectin to cell surfaces is mediated by the amino-terminal 70kDa region of fibronectin. Following the binding of soluble fibronectin to the cell surface, fibronectin-fibronectin interactions are involved in accumulation of fibronectin into disulfide-stabilized aggregates in the extracellular matrix. The goals of this project are to define the structural features of fibronectin that are important for fibronectin matrix assembly, and to determine how specific regions of fibronectin participate in the cell-mediated polymerization of fibronectin into the extracellular matrix. These studies will use variant recombinant fibronectin molecules to investigate which regions of fibronectin are required for matrix assembly, and what role these regions play in this process. Previous data indicate that the sequences necessary for de novo establishment of nucleation sites for matrix assembly are distinct from sequences important for polymerization of fibronectin into preformed matrices. The hypothesis to be tested in this grant is that the first type III module of fibronectin and the integrin- binding site in the 10th type III module of fibronectin are required for the de novo establishment of matrix assembly sites, and that once these sites are established, exogenous fibronectin lacking these sequences can assemble into matrix.