Isolation and partial characterization of lumican and decorin from adult chicken corneas. A keratan sulfate-containing isoform of decorin is developmentally regulated.
The proteoglycans extracted from adult chicken were initially purified by DEAE-chromatography. Digestion of these proteoglycans with chondroitinase ABC generated a single 40-kDa core protein while digestion with keratanase generated a single 52-kDa core protein. Digestion with both enzymes combined, however, increased the amount of 40-kDa core protein produced. This suggested that the 40-kDa core protein exists with chondroitin/dermatan sulfate (C/DS) side chains alone and with both C/DS and keratan sulfate (KS) side chains. The proteoglycan fraction was initially digested with chondroitinase ABC, and the M(r) = 40,000 core protein derived from proteoglycans containing C/DS side chains alone was isolated. Amino-terminal sequencing showed it to be the chick cognate of decorin. The remaining proteoglycans were then digested with keratanase, and both the 40-kDa core protein and the 52-kDa core proteins derived from KS-containing proteoglycans were purified. The M(r) = 40,000 core protein derived from proteoglycans containing both C/DS and KS side chains had the same amino-terminal sequence as decorin and cross-reacted with antibodies to decorin. Sequence from the 52-kDa core protein derived from KS-containing proteoglycans showed it to be lumican. The results of this study suggest that adult chick corneas contain two isoforms of decorin: one containing C/DS side chains and the other, a hybrid, containing both C/DS and KS side chains. Embryonic corneas did not contain the hybrid isoform of decorin. These results suggest that different post-translational modifications occur to the decorin gene product during corneal development and maturation.
Blochberger
T C
TC
Eye & Ear Institute of Pittsburgh, University of Pittsburgh School of Medicine, Pennsylvania 15213.
Cornuet
P K
PK
Hassell
J R
JR
D000818:Animals; D015153:Blotting, Western; D002645:Chickens; D011508:Chondroitin Sulfate Proteoglycans / Q000302:isolation & purification*; D002848:Chromatography, DEAE-Cellulose; D002850:Chromatography, Gel; D003315:Cornea / Q000737:chemistry*; D058575:Decorin; D004591:Electrophoresis, Polyacrylamide Gel; D016326:Extracellular Matrix Proteins; D007632:Keratan Sulfate / Q000302:isolation & purification*; D000071234:Lumican; D008970:Molecular Weight; D011509:Proteoglycans / Q000302:isolation & purification*
D011508:Chondroitin Sulfate Proteoglycans; D058575:Decorin; D016326:Extracellular Matrix Proteins; D000071234:Lumican; D011509:Proteoglycans; D007632:Keratan Sulfate