Structural Biophysics Group, School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff CF24 4LU, UK.
J Struct Biol. 2010 May;170(2):392-7. doi: 10.1016/j.jsb.2010.01.019. Epub 2010 Feb 2.
Corneal transparency is fundamental to the visual system, and is directly related to the ordered collagen fibril architecture that the cornea maintains. Proteoglycans, through their protein core and highly anionic glycosaminoglycan side chains, are thought to regulate the collagen organisation in the corneal stroma. To understand the inter-relationships between proteoglycans and collagen fibrils in the cornea, adult mouse corneas were treated with cuprolinic blue and three-dimensional reconstructions of the anterior, mid and posterior corneal stroma were obtained. The reconstructions show regular diameters of collagen fibrils throughout the cornea and uniform interfibrillar spacing within each region. Both longitudinal and transverse reconstructions were obtained to establish a clear picture of proteoglycan organisation, yet no distinct regular pattern or symmetry of proteoglycan orientation was observed. Large, electron-dense proteoglycans (possibly chondroitin sulphate/dermatan sulphate proteoglycans) interconnecting two or often three adjacent collagen fibrils are seen, whilst another sub-population of smaller proteoglycans (of the keratan sulphate variety) interconnect only neighbouring fibrils. The reconstructions suggest a complex interaction between proteoglycans and collagen, which allows for the dynamic control of collagen fibril architecture in the cornea.
角膜透明性是视觉系统的基础，与角膜维持的有序胶原纤维结构直接相关。蛋白聚糖通过其蛋白核心和高度阴离子化的糖胺聚糖侧链，被认为可以调节角膜基质中的胶原组织。为了了解角膜中蛋白聚糖和胶原纤维之间的相互关系，用 Cuprolinic 蓝处理成年小鼠角膜，并获得了前、中、后角膜基质的三维重建。重建结果显示，整个角膜的胶原纤维直径规则，每个区域的纤维间间距均匀。同时获得了纵向和横向重建，以清晰了解蛋白聚糖的组织，然而，没有观察到蛋白聚糖取向的明显规则模式或对称性。可以看到连接两个或通常三个相邻胶原纤维的大的、电子致密的蛋白聚糖（可能是软骨素硫酸盐/硫酸皮肤素蛋白聚糖），而另一亚群较小的蛋白聚糖（角蛋白硫酸盐类）仅连接相邻的纤维。重建结果表明，蛋白聚糖与胶原之间存在复杂的相互作用，这使得角膜中胶原纤维结构的动态控制成为可能。
