Mechanisms and Effects of Fibronectin Matrix Remodeling

描述（由申请人提供）：正常组织功能需要细胞外基质（ECM）分子（包括胶原蛋白I和纤连蛋白）沉积和降解之间的精确平衡，并且是正常组织修复的关键组成部分。ECM分子的过度或不适当沉积破坏正常组织结构，导致组织力学改变和器官功能受损。控制ECM沉积和周转的机制还不完全清楚。我们的数据表明，纤连蛋白基质聚合调节沉积和保留的几个ECM分子，包括胶原蛋白I。此外，纤连蛋白基质聚合调节细胞-ECM纤维状粘附的组成和稳定性，增强细胞收缩性，并增加基于胶原的组织构建体的机械强度。我们的研究还表明，ECM纤连蛋白和胶原蛋白I的结构组织取决于纤连蛋白基质的连续聚合。破坏纤连蛋白聚合的药剂触发增强的纤连蛋白和胶原I周转;这些药剂还诱导组织中纤连蛋白的周转。这些数据表明，ECM营业额调节，部分，纤连蛋白聚合本身。我们的初步数据表明，纤连蛋白基质周转涉及小窝蛋白-1介导的内吞作用和溶酶体降解。在这个建议中，我们将调查纤连蛋白基质积累的控制机制，并确定纤连蛋白基质重塑的功能后果。我们将使用我们的体外模型系统，采用纤连蛋白空肌成纤维细胞与重组突变纤连蛋白和纤连蛋白片段，以确定纤连蛋白基质聚合控制纤连蛋白的周转和内吞的机制。我们还将测试纤连蛋白基质聚合如何调节培养细胞和组织中细胞-基质纤维粘附位点的形成和稳定性。我们还建立了一个拉伸测试系统，以定量确定组织和胶原蛋白为基础的组织结构的机械性能。我们将使用这个系统来确定纤连蛋白基质周转对细胞收缩性、细胞张力产生和组织机械强度的影响。确定纤连蛋白聚合调节ECM重塑和组织机械强度的机制将为纤维化发展的因素以及可能导致纤维化疾病患者恢复正常基质结构和改善器官功能的机制提供重要见解。

DESCRIPTION (provided by applicant): A precise balance between the deposition and degradation of extracellular matrix (ECM) molecules, including collagen I and fibronectin, is required for normal tissue function, and is a key component of normal tissue repair. Excessive or inappropriate deposition of ECM molecules disrupts normal tissue architecture, leading to altered tissue mechanics and impaired organ function. The mechanisms that control ECM deposition and turnover are incompletely understood. Our data demonstrates that fibronectin matrix polymerization regulates the deposition and retention of several ECM molecules, including collagen I. Furthermore, fibronectin matrix polymerization regulates the composition and stability of cell-ECM fibrillar adhesions, enhances cell contractility, and increases the mechanical strength of a collagen-based tissue construct. Our studies also indicate that the structural organization of ECM fibronectin and collagen I depends upon the continuous polymerization of a fibronectin matrix. Agents that disrupt fibronectin polymerization trigger enhanced fibronectin and collagen I turnover; these agents also induce turnover of fibronectin in tissues. This data suggests that ECM turnover is regulated, in part, by fibronectin polymerization itself. Our preliminary data indicate that fibronectin matrix turnover involves caveolin-1 mediated endocytosis and lysosomal degradation. In this proposal, we will investigate the mechanisms by which fibronectin matrix accumulation is controlled, and determine the functional consequences of fibronectin matrix remodeling. We will use our in vitro model system employing fibronectin-null myofibroblasts in conjunction with recombinant mutant fibronectins and fibronectin fragments to determine the mechanisms by which fibronectin matrix polymerization controls the turnover and endocytosis of fibronectin. We will also test how fibronectin matrix polymerization regulates the formation and stability of cell-matrix fibrillar adhesion sites in cultured cells and in tissues. We have also established a tensile testing system to quantitatively determine the mechanical properties of tissues and collagen-based tissue constructs. We will use this system to determine the effects of fibronectin matrix turnover on cell contractility, cell tension generation, and the mechanical strength of tissues. Determining the mechanisms by which fibronectin polymerization regulates ECM remodeling and tissue mechanical strength will provide important insights into factors that contribute to the development of fibrosis, and into mechanisms that could lead to restoration of normal matrix architecture and improved organ function in individuals with fibrotic disorders.