Isolation and partial characterization of lumican and decorin from adult chicken corneas. A keratan sulfate-containing isoform of decorin is developmentally regulated.
1992; Elsevier BV; Volume: 267; Issue: 29 Linguagem: Inglês
10.1016/s0021-9258(19)36731-6
ISSN1083-351X
AutoresThomas C. Blochberger, Pamela Cornuet, John R. Hassell,
Tópico(s)Polysaccharides Composition and Applications
ResumoThe 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 , = 40,000 core protein derived from proteoglycans containing C/DS side chains alone was isolated.Aminoterminal 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 KScontaining proteoglycans were purified.The M, = 40,000 core protein derived from proteoglycans containing both C P S 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 P S 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.The cornea is composed of three layers: an epithelial cell layer, a stroma layer, consisting of an extensive extracellular matrix interspersed with fibroblasts, and an endothelial cell layer (1, 2).The stromal matrix, which is made and maintained by the fibroblasts, is primarily composed of collagen fibrils and proteoglycans.Biochemical and immunologic characterization of proteoglycans isolated from corneas of different species, such as rabbit (3,4), bovine (5-7), monkey (8,9), and embryonic chick (10-13), indicate there are at least two
Referência(s)