CADHERIN DYNAMICS AND GLAUCOMA

描述(申请人提供)：最近的临床试验表明，青光眼患者显著、持续的眼压降低会减缓或阻止视力丧失，即使是在低眼压性青光眼患者中也是如此。虽然青光眼中阻力增加的部位可能位于常规的引流途径中，但导致这种额外阻力产生的细胞机制尚不清楚。以前的工作指出了两种不相互排斥的可能性：(I)管旁组织细胞外基质物质的异常堆积和/或改变；或(Ii)Schlemm管内壁细胞间连接(和相关的边界孔)功能的改变。在目前的应用中，我们建议研究Schlemm管内皮细胞中的细胞-细胞黏附分子家族--钙粘附素。钙粘附素形成粘附性连接复合体，存在于传统的引流途径中，但仅在形态上进行了描述。由于相邻细胞上钙粘蛋白胞外区的亲水性蛋白质相互作用对于形成和维持至少三种细胞间连接复合体(包括粘附物、闭塞物和缝隙)的完整性至关重要，而且已发表的证据表明细胞-细胞黏附在决定流出阻力中发挥作用，我们推测Schlemm管内皮细胞之间的钙粘附素强烈影响流出阻力的产生。我们的研究将在分子和功能水平上研究钙粘蛋白，(I)特异性靶向钙粘蛋白-5(加上相关的连接素蛋白)并破坏Schlemm管内皮细胞之间的黏附；(Ii)分析压力差/拉伸对钙粘蛋白-5和相关连接素的相对表达水平、亚细胞分布和磷酸化状态的影响；以及(Iii)监测调节钙粘蛋白-5连接复合体的形成和重塑的信号蛋白。这些研究的结果将提供对钙粘蛋白蛋白在房水流出阻力中的作用的基本了解，并揭示青光眼治疗的新治疗靶点。

DESCRIPTION (provided by applicant): Recent clinical trials demonstrate that significant, sustained intraocular pressure reduction in people with glaucoma slows or halts vision loss, even in patients with low-tension glaucoma. While the site of increased resistance in glaucoma is likely located in the conventional drainage pathway, the cellular mechanisms responsible for generation of this extra resistance are unknown. Previous work points to two possibilities that are not mutually exclusive: (i) abnormal accumulation and/or alterations in the extracellular matrix materials of the juxtacanalicular tissue; or (ii) alterations in the function of the intercellular junctions (and associated border pores) of the inner wall of Schlemm's canal. In the present application, we propose to study a family of cell-cell adhesion molecules, the cadherins, in the endothelial cells of Schlemm's canal. Cadherins form adherens junctional complexes, which are present in the conventional drainage pathway, but have only been described morphologically. Since homophilic protein- protein interactions of cadherin extracellular domains on adjacent cells are critical to the formation and maintenance of the integrity of at least three intercellular junctional complexes (including adherens, occludens and gap), and published evidence suggests that cell-cell adhesion plays a role in determining outflow resistance, we hypothesize that cadherins between Schlemm's canal endothelia strongly influence the generation of outflow resistance. Our study will examine cadherins at the molecular and functional levels and (i) specifically target cadherin-5 (plus associated catenin proteins) and disrupt adhesion between Schlemm's canal endothelia; (ii) analyze effects of pressure differences/stretch on relative expression levels, subcellular distribution and phosphorylation status of cadherin-5 plus associated catenins; and (iii) monitor signaling proteins that regulate the formation and remodeling of the cadherin-5 junction complex. Results obtained from these investigations will provide a basic understanding of the role of cadherin proteins in aqueous outflow resistance and uncover novel therapeutic targets for glaucoma therapy.