Proteoglycan biosynthesis by human corneas from patients with types 1 and 2 macular corneal dystrophy

• Published in: The Journal of biological chemistry 1990-09, Vol.265 (26), p.15947-15955
• Main Authors: MIDURA, R. J, HASCALL, V. C, MACCALLUM, D. K, MEYER, R. F, THONAR, E. J.-M. A, HASSELL, J. R, SMITH, C. F, KLINTWORTH, G. K
• Format: Article
• Language: English
• Subjects: 550901 - Pathology- Tracer Techniques; ALDEHYDES; AMINES; BASIC BIOLOGICAL SCIENCES; Biological and medical sciences; BIOSYNTHESIS; BODY; BODY AREAS; CARBOHYDRATES; Cells, Cultured; CHROMATOGRAPHY; Chromatography, Ion Exchange; CORNEA; Cornea - metabolism; Corneal Dystrophies, Hereditary - metabolism; DISEASES; Diseases of cornea, anterior segment and sclera; EYES; FACE; GLUCOSAMINE; Glucosamine - metabolism; GLYCOPROTEINS; Glycoproteins - biosynthesis; Glycoproteins - isolation & purification; HEAD; HEXOSAMINES; HEXOSES; Humans; HYDROGEN COMPOUNDS; ISOTOPE APPLICATIONS; Keratoconus - metabolism; macular corneal dystrophy; MANNOSE; Mannose - metabolism; Medical sciences; Molecular Weight; MONOSACCHARIDES; Ophthalmology; ORGANIC COMPOUNDS; ORGANS; PATHOGENESIS; PATIENTS; PROTEINS; Proteoglycans - biosynthesis; Proteoglycans - isolation & purification; Reference Values; SACCHARIDES; SENSE ORGANS; SENSE ORGANS DISEASES; SEPARATION PROCESSES; SYNTHESIS; TRACER TECHNIQUES; Tritium; TRITIUM COMPOUNDS
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(18)55489-2

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.