Keratan sulfate

About: Keratan sulfate is a research topic. Over the lifetime, 1253 publications have been published within this topic receiving 57984 citations. The topic is also known as: keratan sulfate & KS.

Significant decrease in α1,3-linked fucose in association with increase in 6-sulfated N-acetylglucosamine in peripheral lymph node addressin of FucT-VII-deficient mice exhibiting diminished lymphocyte homing

Abstract: Lymphocyte homing is mediated by binding of L-selectin on lymphocytes with L-selectin ligands present on highendothelial venules (HEV) of peripheral and mesenteric lymph nodes. L-selectin ligands are specific O-linked carbohydrates, 6-sulfo sialyl Lewis X, composed of sialylated, fucosylated, and sulfated glycans. Abrogation of fucosyltransferase-VII (FucT-VII) results in almost complete loss of lymphocyte homing, but structural analysis of carbohydrates has not been carried out on FucT-VII null mice. To determine whether functional losses seen in FucT-VII null mice are caused by structural changes in carbohydrates, we elucidated the carbohydrate structure of GlyCAM-1, a major L-selectin counter-receptor. Our results show that most a1,3-fucosylated structures in 6-sulfo sialyl Lewis X are absent and 6-sulfo N-acetyllactosamine is increased in the mutant mice. Surprisingly, the amount of 6 0 -sulfated galactose (Gal) that bound to Sumbucus nigra agglutinin column was also increased. We found that structures of those oligosaccharides containing 6 0 -sulfated Gal are almost identical to those synthesized by keratan sulfate sulfotransferase (KSST). We then showed that overexpression of KSST suppresses the expression of sialyl Lewis X on Chinese hamster ovary (CHO) cells engineered to express sialyl Lewis X. Moreover, KSST expression in those cells suppressed lymphocyte rolling compared with mock-transfected CHO cells expressing 6-sulfo sialyl Lewis X. 6 0 -Sulfo sialyl Lewis X can neither be found in GlyCAM-1 from CHO cells expressing both KSST and FucT-VII nor be found in GlyCAM-1 from HEV of mice. These results combined together suggest that KSST competes with FucT-VII for the same acceptor substrate and downregulates the synthesis of L-selectin ligand by inhibiting a1,3-fucosylation.

Heterogeneity, polydispersity, and physiologic role of corneal proteoglycans.

Abstract: Gel chromatography, affinity chromatography, ultracentrifugation, enzymic fragmentation, and analysis of amino acids, hexosamines and neutral sugars were used to characterize a heterogeneous fraction of proteoglycans from bovine corneal stroma. The results indicate that the fraction largely consists of a mixture of the 2 main types of corneal proteoglycans described earlier, namely keratan sulfate proteoglycans and chondroitin sulfate-rich proteoglycans with covalently bound oligosaccharides. Models for the structure of proteoglycans are suggested, an it is concluded that the molecular size of corneal proteoglycans makes them appropriate as ‘spacers’ between the collagen fibrils, a property important for corneal transparency. Cornea is softer than cartilage because corneal proteoglycans are less underhydrated than cartilage proteoglycans.

Immunoglobulin G and serum albumin isolated from the articular cartilage of patients with rheumatoid arthritis or osteoarthritis contain covalent heteropolymers with proteoglycans.

Abstract: The present study was undertaken to identify the cartilage matrix molecules that are bound with intermolecular disulfide bonds to IgG and serum albumin molecules recovered from the articular cartilage of patients with rheumatoid arthritis (RA) or osteoarthritis (OA). The cartilage specimens were extracted sequentially with three changes of neutral buffer, three changes of 6 M guanidine hydrochloride and then partiallydegraded with bacterial collagenase. The extracted IgG and albumin, along with matrix molecules bound to these proteins, were isolated with affinity chromatography using antibodies to IgG or human serum albumin conjugated to agarose beads. The isolated materials were characterized with sodium dodecyl sulfate polyacrylamide gel electrophoresis and transfer blotting, using specific antibodies to IgG, albumin, and proteoglycans. In the isolated materials, heteropolymers with IgG or albumin wer identified. These polymers contained keratan sulfate and less frequently chondroitin-4-sulfate and chondroitin-6-sulfate. These findings identified the keratan sulfate rich proteoglycans, prevalent at the surface of joint cartilage, as the most common cartilage matrix molecules that are covalently bound to IgG or to serum albumin by disulfide bonds in the articular cartilage of patients with RA or OA.

Electron microscopy of proteoglycans

Abstract: In addition to the fibrillar proteins collagen and elastin, proteoglycans constitute a major macro-molecular component in the extracellular matrix of connective tissues. They have also been identified as components of basement membranes and cell surface coats. Chemically, the proteoglycans consist of a protein core to which glycosaminoglycan chains are covalently attached. The latter are composed of alternating uronic acid and hexosamine residues and are all polyanions with acidic sulfate and/or carboxyl groups (1). A particularly high content of proteoglycans is found in cartilage and much of the information that is available today derives from studies on this tissue. An average cartilage proteoglycan has a molecular weight of about 2.5 af09106 and is composed of a protein core to which about 100 chon-droitin sulfate and 50–60 keratan sulfate chains are bound. Within the cartilaginous matrix, most of these monomers occur in large aggregates, formed by noncovalent interaction with hyaluronic acid and link proteins (2–4). The structure of proteoglycans in other connective tissues, in basement membranes, and in cell surface coats is less well known. The type, number, and size of glycosaminoglycan chains per molecule have been found to vary considerably, but the supramolecular organization (e.g. aggregate formation) is still poorly defined.