Proteoglycan biosynthesis by human corneas from patients with types 1 and 2 macular corneal dystrophy.
Proteoglycan biosynthesis by human corneas from patients with types 1 and 2 macular corneal dystrophy.
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发表时间：
1990-09
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通讯作者：
R. Midura;V. Hascall;D. Maccallum;R. Meyer;E. Thonar;J. Hassell;C. F. Smith;G. Klintworth
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作者：
R. Midura;V. Hascall;D. Maccallum;R. Meyer;E. Thonar;J. Hassell;C. F. Smith;G. Klintworth
角膜纽扣取自1型和2型黄斑角膜营养不良（MCD）患者以及Fuchs营养不良或圆锥角膜的对照患者。在[3 H]葡糖胺或[2- 3 H]甘露糖存在下孵育20小时。放射性标记的蛋白聚糖和乳糖胺聚糖-糖蛋白（L-GP）使用色谱法在Q-Sepharose、Superose 6和辛基-Sepharose上纯化。采用软骨素酶ABC、角蛋白酶或内切-β-半乳糖苷酶消化、十二烷基硫酸钠-聚丙烯酰胺凝胶电泳或Superose 6色谱法对它们进行鉴定。本研究证实了先前的报告，即1型MCD角膜合成正常的硫酸皮肤素蛋白聚糖（DS-PG）和异常的硫酸角质素蛋白聚糖（KS-PG）。数据表明，1型MCD角膜合成L-GP而不是KS-PG。该L-GP具有与KS-PG的核心蛋白相似的疏水性（从辛基琼脂糖凝胶洗脱）和几乎相似的质量（42 kDa）的核心蛋白。它具有与KS-PG相同的糖缀合物，除了它们缺乏硫酸盐。因此，1型MCD由于对硫酸化乳糖胺聚糖具有特异性的磺基转移酶缺陷而不能合成硫酸角质素。此外，研究了2型MCD患者角膜合成的蛋白聚糖。该角膜合成了正常比例的KS-PG与DS-PG，尽管蛋白聚糖的净合成低于正常水平约30%。KS-PG表现正常，而DS-PG具有比正常短约40%的硫酸皮肤素链。
Corneal buttons were obtained from patients with types 1 and 2 macular corneal dystrophy (MCD) and from control patients with Fuchs' dystrophy or keratoconus. Buttons were incubated for 20 h in the presence of [3H]glucosamine or [2-3H]mannose. Radiolabeled proteoglycans and lactosaminoglycan-glycoproteins (L-GPs) were purified using chromatography on Q-Sepharose, Superose 6, and octyl-Sepharose. They were identified using chondroitinase ABC, keratanase or endo-beta-galactosidase digestion, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis or Superose 6 chromatography. This study confirms previous reports that type 1 MCD corneas synthesize a normal dermatan sulfate-proteoglycan (DS-PG) and an abnormal keratan sulfate-proteoglycan (KS-PG). The data indicate that typ 1 MCD corneas synthesize L-GP instead of KS-PG. This L-GP has a core protein of similar hydrophobicity (elution from octyl-Sepharose) and nearly similar mass (42 kDa) as the core protein of the KS-PG. It has identical glycoconjugates as those of the KS-PG except that they lack sulfate. Thus, type 1 MCD fails to synthesize keratan sulfate as a result of a defect in a sulfotransferase specific for sulfating lactosaminoglycans. Further, proteoglycans synthesized by a cornea from a patient with type 2 MCD were studied. This cornea synthesized a normal ratio of KS-PG to DS-PG although net synthesis of proteoglycans was approximately 30% below normal. The KS-PG appeared normal whereas the DS-PG had dermatan sulfate chains that were approximately 40% shorter than normal.