Corneal Repair: uPA and extracellular matrix

角膜修复：uPA 和细胞外基质

• 批准号: 7015385
• 负责人: AUDREY M BERNSTEIN
• 金额: $ 30.59万
• 依托单位: ICAHN SCHOOL OF MEDICINE AT MOUNT SINAI
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-06-01 至 2011-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7015385
• 关键词: cell migration; cornea; endopeptidases; extracellular matrix; fibroblasts; growth factor; integrins; plasmin; wound healing

DESCRIPTION (provided by applicant): Corneal wound healing without scarring regenerates corneal transparency. Corneas that heal with scarring have opacities and obstructed vision. Thus, understanding the pathways that influence regenerative rather than fibrotic healing is an essential step towards therapeutically promoting healthy repair. Upon corneal wounding, the normally quiescent cells in the stroma differentiate into fibroblasts, which secrete proteases as they migrate. This proposal is focused on the contributions of the extracellular serine protease, urokinase-type plasminogen activator (uPA), which is expressed by corneal fibroblasts after wounding. When uPA binds to its cell-surface receptor, uPAR, uPA generates plasmin at the cell-matrix interface. Plasmin degrades extracellular matrix (ECM) and activates latent growth factors such as TGFB. TGFB stimulates fibroblast proliferation and migration, and induces the differentiation of motile fibroblasts into non-motile myofibroblasts, which are essential for matrix contraction and wound closure. 1 way in which TGFB may be eliciting its dual effects is through the induction of plasminogen activation inhibitor (PAI-1) expression. There is a significant body of data that the opposing effects of PAI-1 are concentration dependent: low concentrations of PAI-1 induce cell proliferation and migration, whereas, high concentrations inhibit these processes. The hypothesis being tested in this proposal is that after corneal wounding, local PAI-1 concentrations are mediated by binding to Vn. Further, that low concentrations of PAI-1 result in corneal fibroblast proliferation and migration whereas high concentrations of PAI-1 induce uPA/uPAR downregulation and result in myofibroblast differentiation. The specific aims are to determine if 1) TGFB concentration regulates PAI-1 levels, uPA activity, and myofibroblast differentiation. 2) Vn mediates the effects of TGFB and PAI-1 on uPA activity, cell migration, and myofibroblast differentiation. 3) Vn, PAI-1 and integrin expression change throughout wound healing with changing stromal phenotypes. 4) uPAR cleavage into a non-uPA binding form inhibits cell migration and induces myofibroblast differentiation. The results of these studies will lead to a better understanding of the mechanisms that guide regenerative wound repair.

描述（由申请人提供）：角膜伤口愈合且不留疤痕，可恢复角膜透明度。疤痕愈合后的角膜会出现混浊和视力障碍。因此，了解影响再生而不是纤维化愈合的途径是治疗促进健康修复的重要一步。角膜受伤后，基质中通常静止的细胞分化为成纤维细胞，成纤维细胞在迁移时分泌蛋白酶。该提案的重点是细胞外丝氨酸蛋白酶、尿激酶型纤溶酶原激活剂（uPA）的贡献，它在受伤后由角膜成纤维细胞表达。当 uPA 与其细胞表面受体 uPAR 结合时，uPA 在细胞基质界面处产生纤溶酶。纤溶酶降解细胞外基质 (ECM) 并激活潜在生长因子，例如 TGFB。 TGFB 刺激成纤维细胞增殖和迁移，并诱导活动成纤维细胞分化为非活动肌成纤维细胞，这对于基质收缩和伤口闭合至关重要。 TGFB 可能引发其双重作用的一种方式是通过诱导纤溶酶原激活抑制剂 (PAI-1) 的表达。有大量数据表明，PAI-1 的相反作用是浓度依赖性的：低浓度的 PAI-1 诱导细胞增殖和迁移，而高浓度则抑制这些过程。该提案中测试的假设是，角膜受伤后，局部 PAI-1 浓度是通过与 Vn 结合介导的。此外，低浓度的PAI-1导致角膜成纤维细胞增殖和迁移，而高浓度的PAI-1诱导uPA/uPAR下调并导致肌成纤维细胞分化。具体目的是确定 1) TGFB 浓度是否调节 PAI-1 水平、uPA 活性和肌成纤维细胞分化。 2) Vn介导TGFB和PAI-1对uPA活性、细胞迁移和肌成纤维细胞分化的影响。 3) Vn、PAI-1 和整合素表达在整个伤口愈合过程中随着基质表型的变化而变化。 4) uPAR裂解成非uPA结合形式抑制细胞迁移并诱导肌成纤维细胞分化。这些研究的结果将有助于更好地理解指导再生伤口修复的机制。