METALLOPROTEINASE IN NORMAL AND KERATOCONUS CORNEAS

圆锥角膜（KC）是一种人类角膜的异常变薄， 主要是年轻人。 它的发病率为2,000分之一， 这是美国角膜移植的主要原因。 在 在过去的一段时间内，PI确定，在KC角膜和KC中， 基质金属蛋白酶-2（MMP-2） 活动与正常相比。假设是MMP-2及其 相关的金属蛋白酶组织抑制剂（TIMPs）是重要的 在最终导致角膜变薄的一连串事件中， 正常调节MMP-2活性的机制被改变 在KC角膜中。 由此产生的蛋白酶活性的增加影响两个 角膜区域、上皮基底膜/Bowman层和 细胞外基质（ECM）的结构成分。 一个重要 活性增加的靶点可以是VI型胶原，其充当免疫调节剂。 蛋白聚糖和胶原纤维之间的稳定物质， 基质。为了阐明基质金属蛋白酶在KC病因学中的作用，PI 建议：1）确定MMP-2的结构是否存在缺陷 和/或导致异常酶活性的TIMP; 2） 确定KC角膜是否存在TIMP-3的改变（新描述 抑制剂）和/或MT-MMP（MMP-2细胞膜结合激活剂）; 3） 确定角膜ECM成分，XII型胶原蛋白和 蛋白聚糖对MMP-2敏感; 4）确定切割后 与MMP-2、VI型胶原和其它敏感ECM组分相互作用 通常与胶原蛋白和蛋白聚糖; 5）鉴定基因， 在KC中差异表达。拟议的研究将大大 促进我们对KC的理解和基因表达的变化， 导致这种紊乱。此外，这些研究还将提供基本的 关于正常角膜中MMP活性调节的信息， 蛋白酶作用对角膜ECM结构的影响， organization.

Keratoconus (KC) is an abnormal thinning of the human cornea affecting mainly younger individuals. It has an incidence of 1 in 2,000 and is now a leading cause for corneal transplantation in the United States. In the past period the PI established that, in both KC corneas and KC keratocytes, there is an increase in matrix metalloproteinase-2 (MMP-2) activity compared to normal. The hypothesis is that MMP-2 and its associated tissue inhibitors of metalloproteinases (TIMPs) are important in the cascade of events which ultimately results in corneal thinning and that the mechanism(s) which normally regulates MMP-2 activity is altered in the KC cornea. The resulting increase in protease activity affects two areas of the Cornea, the epithelial basement membrane/Bowman's layer and structural components of the extracellular matrix (ECM). An important target of the increased activity may be type VI collagen, which acts as a stabilizing substance between proteoglycans and the collagen fibrils in the stroma. To clarify the role of MMPs in the etiology of KC, the PI proposes to: 1)Determine if there are defects in the structure of MMP-2 and/or TIMPs which would account for the abnormal enzyme activity; 2) Determine if KC corneas have an alteration in TIMP-3 (newly described inhibitor) and/or MT-MMP (cell membrane bound activator of MMP-2); 3) Determine if corneal ECM components, e.g., type XII collagen and proteoglycans, are susceptible to MMP-2; 4) Determine if after cleavage with MMP-2, type VI collagen and other susceptible ECM components interact normally with collagens and proteoglycans; 5) Identify genes which are differentially expressed in KC. The proposed studies will significantly advance our understanding of KC and the changes in gene expression which lead to this disorder. In addition, these studies will also provide basic information on the regulation of MMP activity in the normal cornea and the consequences of protease action on corneal ECM structure and organization.