KERATOCYTE COLLAGENASE INDUCED VIA FIBRONECTIN RECEPTOR

正常的眼睛功能依赖于角膜的透明度，而角膜透明度又反过来， 取决于维持正常的角膜基质。《间质》 角质形成细胞通常是静止的，可以被刺激合成和 分泌中性蛋白酶和细胞外基质。在基质伤口中 修复和重塑，降解现有的细胞外基质和 新的细胞外基质的合成必须在空间上控制和 暂时的。胶原酶分泌过多会导致角膜溃疡或 融化了。细胞因子和细胞骨架干扰物，如细胞松弛素B和 佛波醇诱导胶原酶。胶原酶活性受调控 转录和细胞外抑制物(TIMP)或激活剂。 我们提供了初步数据，角质细胞胶原酶是通过一种 纤维连接蛋白信号转导通路。我们假设角质形成细胞 纤维连接蛋白受体(整合素)区分完整的纤维连接蛋白和 纤维连接蛋白片段：一个或多个识别序列 纤维连接蛋白片段被认为是降解产物，激活了 纤维连接蛋白受体介导的角质细胞胶原酶途径。 我们的具体目标是： 1.更准确地定义细胞外基质信号 胶原酶诱导。有纤维粘连蛋白的结构域(S)或其他 调节金属蛋白酶的细胞外基质成分 分泌物？ 2.鉴定角膜基质细胞的整合素，并确定 它们的相对数量由纤维连接蛋白的内吞作用或由 诱导胶原酶的刺激物。 3.从形态上，通过动力学和定量测定， 原胶原酶诱导和前胶原酶诱导之间是否存在严格的相关性 肌动蛋白细胞骨架的变化。 4.通过纤维连接蛋白受体确定差异调节。 新的细胞外基质合成和蛋白酶合成/活性。 具体地说，胶原酶、胶原、纤维连接蛋白和TIMP是由 在促进新的合成或降解的模式中？这有可能吗？ 在一个单独的细胞中演示？ 这些研究将有助于理解角膜伤口愈合，其中 角质形成细胞降解并重新合成细胞外基质。 了解胶原酶的调节机制将有助于预防 由于不受抑制的胶原酶分泌造成的损害，如圆锥角膜。我们的 长期目标是在细胞、亚细胞和 分子水平上细胞外基质和个体 正常和病理性角膜基质细胞在时间和空间上的相互作用 伤口愈合或圆锥角膜等情况。

Normal eye function depends on corneal transparency which, in turn, depends on maintenance of a normal corneal stroma. The stromal keratocyte, normally quiescent, can be stimulated to synthesize and secrete neutral proteinases and extracellular matrix. In stromal wound healing and remodeling, degradation of existing extracellular matrix and synthesis of new extracellular matrix must be controlled spatially and temporally. Excess collagenase secretion causes corneal ulceration or melting. Cytokines and cytoskeletal disruptors like cytochalasin B and phorbol induce collagenase. Collagenase activity is regulated transcriptionally and by extracellular inhibitors (TIMP) or activators. We present preliminary data that keratocyte collagenase is induced via a fibronectin signal transduction pathway. We hypothesize that keratocyte fibronectin receptors (integrins) distinguish intact fibronectin from fibronectin fragments: one or more recognition sequences in the fibronectin fragment, sensed as degradation products, activate the keratocyte collagenase pathway via fibronectin receptors. Our specific aims are to: 1. Define more precisely the extracellular matrix signals for collagenase induction. Are there domain(s) of fibronectin or other extracellular matrix components which regulate metalloproteinase secretion? 2. Identify the integrins of corneal keratocytes and determine whether their relative number is regulated by endocytosis of fibronectin or by stimuli which induce collagenase. 3. Determine morphologically, and by kinetic and quantitative assays, whether a strict correlation exists between procollagenase induction and changes in the actin cytoskeleton. 4. Determine differential regulation through the fibronectin receptor of new extracellular matrix synthesis and proteinase synthesis/activity. Specifically, are collagenase, collagen, fibronectin, and TIMP induced in patterns which promote new synthesis or degradation? Can this be demonstrated in an individual cell? These studies will aid understanding of corneal wound healing, in which keratocytes degrade and re-synthesize extracellular matrix. Understanding mechanisms of collagenase regulation will help prevent damage from uninhibited collagenase secretion, as in keratoconus. Our long term goal is to determine at the cellular, subcellular and molecular level how the extracellular matrix and the individual keratocyte interact temporally and spatially in normal and pathological situations such as wound healing or keratoconus.