CADHERIN DYNAMICS AND GLAUCOMA

描述（由申请人提供）：最近的临床试验表明，青光眼患者显著、持续的眼压降低可以减缓或停止视力下降，即使是低压型青光眼患者。虽然青光眼中阻力增加的部位可能位于传统的排水通路，但产生这种额外阻力的细胞机制尚不清楚。先前的工作指出了两种并非相互排斥的可能性：(i)关节旁组织细胞外基质物质的异常积累和/或改变；或（ii）施勒姆管内壁细胞间连接（及相关的边界孔）功能的改变。在目前的应用中，我们建议研究一类细胞-细胞粘附分子，钙粘蛋白，在施莱姆管内皮细胞。钙粘蛋白形成粘附连接复合物，存在于常规的排水途径中，但仅在形态学上进行了描述。由于邻近细胞上钙粘蛋白胞外结构域的亲同蛋白-蛋白相互作用对至少三种细胞间连接复合物（包括粘附体、occludens和间隙）的形成和维持完整性至关重要，并且已发表的证据表明细胞-细胞粘附在决定流出阻力中起作用，因此我们假设施莱姆管内皮之间的钙粘蛋白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检查钙粘蛋白，并且(i)专门针对钙粘蛋白-5（加上相关的连环蛋白）并破坏施莱姆管内皮之间的粘附；（ii）分析压力差/拉伸对cadherin-5及相关连环蛋白的相对表达水平、亚细胞分布和磷酸化状态的影响；（iii）监测调节钙粘蛋白-5连接复合体形成和重塑的信号蛋白。这些研究结果将为钙粘蛋白在水流出阻力中的作用提供基本的认识，并为青光眼治疗提供新的治疗靶点。

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.