Analysis of newly synthesized Bruch's membrane proteoglycans.
Analysis of newly synthesized Bruch's membrane proteoglycans.
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DOI：
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发表时间：
1989-03
影响因子：
4.4
通讯作者：
A. Hewitt;K. Nakazawa;D. A. Newsome
中科院分区：
文献类型：
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作者：
A. Hewitt;K. Nakazawa;D. A. Newsome
Bruch膜可能为从脉络膜毛细血管进入视网膜外层的营养物质提供了一种选择性的过滤屏障。由于蛋白多糖已被证明在其他组织中具有结构和过滤特性，我们一直在研究新合成的蛋白多糖在Bruch膜中的沉积以及这些沉积可能如何受到衰老和病理的影响。在全眼器官培养系统中，用~(35)SO_4和~3H-氨基葡萄糖代谢性标记沉积在人Bruchs膜上的蛋白多糖。用4-甲基胍从分离的Bruch膜中提取标记的蛋白多糖，并用DEAE纤维素线性盐梯度离子交换柱层析分离。这些分子随后在SepharoseCL-4B上进行了层析，并用酶法和化学降解法表征了糖胺多糖的含量。蛋白多糖的洗脱曲线随着年龄的增长保持相对不变，尽管在70岁以上的捐赠者的眼睛中，大小分布有微小的变化，倾向于更高的分子质量。然而，新合成的糖胺多糖的比例随着年龄的增长保持不变，约为75%的硫酸软骨素/皮肤素和25%的硫酸肝素。然而，来自不同视网膜病变供体的Bruchs膜蛋白多糖显示出更高比例的硫酸乙酰肝素。考虑到蛋白多糖的结构和过滤特性，这种变化可能导致Bruch膜的异常功能，最终可能影响外视网膜的维持。
Bruch's membrane may provide a selective filtration barrier for nutrients coming from the choriocapillaris to the outer retina. Because proteoglycans have been shown to have structural and filtration properties in other tissues, we have been investigating the deposition of newly synthesized proteoglycans into Bruch's membrane and how these may be affected by aging and pathology. Proteoglycans deposited in human Bruch's membrane were metabolically labelled with 35SO4 and 3H-glucosamine using a whole-eye organ culture system. Labeled proteoglycans were extracted from dissected Bruch's membranes with 4 M guanidine and isolated by ion-exchange column chromatography on DEAE cellulose using a linear salt gradient. These molecules were subsequently chromatographed on Sepharose CL-4B and glycosaminoglycan content characterized by enzymatic and chemical degradation. The elution profiles for proteoglycans remains relatively unchanged with age, although in eyes from donors over age 70 there is a small change in size distribution toward higher molecular weights. However, the proportions of newly synthesized glycosaminoglycans remain unchanged with age, being approximately 75% chondroitin sulfate/dermatan sulfate and 25% heparan sulfate. Bruch's membrane proteoglycans from donors with different retinal pathologies, however, exhibited an increased proportion of heparan sulfate. Considering the structural and filtration properties of proteoglycans, such alterations could result in abnormal functioning of Bruch's membrane that could ultimately affect the maintenance of the outer retina.