Macular Corneal Dystrophy: Failure to Synthesize a Mature Keratan Sulfate Proteoglycan

Corneal specimens obtained during surgery from patients with macular corneal dystrophy and obtained at autopsy from control eyes were incubated in a medium containing radioactive precursors of glycoproteins and proteoglycans. Biosynthetically radiolabeled material was extracted and characterized by...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 1980-06, Vol.77 (6), p.3705-3709
Main Authors: Hassell, John R., Newsome, David A., Krachmer, Jay H., Rodrigues, Merlyn M.
Format: Article
Language:English
Subjects:
Chondroitin Sulfate Proteoglycans - biosynthesis
Chondroitin Sulfate Proteoglycans - deficiency
Chondroitin Sulfate Proteoglycans - genetics
Chromatography
Chromatography, Agarose
Cornea
Cornea - analysis
Cornea - metabolism
Corneal Dystrophies, Hereditary - genetics
Corneal Dystrophies, Hereditary - metabolism
Glycoproteins
Glycoproteins - metabolism
Glycosaminoglycans
Glycosaminoglycans - deficiency
Humans
Keratan Sulfate - biosynthesis
Keratan Sulfate - deficiency
Keratan Sulfate - genetics
Lumican
Molecular weight
Oligosaccharides
Organ Culture Techniques
Peptide Fragments - analysis
Proteoglycans
Proteoglycans - deficiency
Radioactive decay
Sulfates
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Summary:Corneal specimens obtained during surgery from patients with macular corneal dystrophy and obtained at autopsy from control eyes were incubated in a medium containing radioactive precursors of glycoproteins and proteoglycans. Biosynthetically radiolabeled material was extracted and characterized by using molecular sieve chromatography and specific enzymes. Cells in control corneas synthesized both a chondroitin sulfate proteoglycan and a keratan sulfate proteoglycan similar to those present in monkey and bovine corneas. Cells in macular corneas synthesized a normal chondroitin sulfate proteoglycan but did not synthesize either keratan sulfate or a mature keratan sulfate proteoglycan. Instead, macular corneas synthesized a glycoprotein with unusually large oligosaccharide side chains. This glycoprotein was not detected in normal corneas and is slightly smaller than normal keratan sulfate proteoglycan. The failure to synthesize a mature keratan sulfate proteoglycan may produce corneal opacity and result in blindness. Because of evidence indicating that the corneal keratan sulfate proteoglycan is normally synthesized through a glycoprotein intermediate [Hart, G. W. & Lennarz, W. (1978) J. Biol. Chem. 253, 5795-5801], macular corneal dystrophy may be a defect in glycoprotein processing.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.77.6.3705