Disease relevance of LUM

• The failure to synthesize a mature keratan sulfate proteoglycan may produce corneal opacity and result in blindness [1].
• There was no significant difference in the amount of KSPG core protein antigens in keratoconus and normal corneal extracts [2].
• Different aspects of HA type/subtype and phenotype LDC VP of Aeromonas strains are discussed [3].

High impact information on LUM

• Bone matrix proteins: isolation and characterization of a novel cell-binding keratan sulfate proteoglycan (osteoadherin) from bovine bone [4].
• Cells in macular corneas synthesized a normal chondroitin sulfate proteoglycan but did not synthesize either keratan sulfate or a mature keratan sulfate proteoglycan [1].
• This glycoprotein was not detected in normal corneas and is slightly smaller than normal keratan sulfate proteoglycan [1].
• Fibroblast growth factor-2 promotes keratan sulfate proteoglycan expression by keratocytes in vitro [5].
• Combined with serum, FGF-2 also prevented serum-induced KSPG down-regulation [5].

Chemical compound and disease context of LUM

• These results suggest that corneas with keratoconus contain a form of KSPG that contains fewer keratan sulfate chains or in which the keratan sulfate has a modified structure [2].

Biological context of LUM

• The bovine cDNA codes for a 342-amino acid protein, M(r) 38,712, containing amino acid sequences identified in the 37B KSPG core protein [6].
• Unique glycosylation of three keratan sulfate proteoglycan isoforms [7].
• Downregulation of microglial KSPG could be a prerequisite for a rapid inflammatory response in the central nervous system [8].
• Molecular cloning and tissue distribution of keratocan. Bovine corneal keratan sulfate proteoglycan 37A [9].
• Addition of fetal bovine serum, fibroblast growth factor-2 (FGF-2), transforming growth factor beta, or platelet derived growth factor all stimulated cell division, but only FGF-2 stimulated KSPG secretion [5].

Anatomical context of LUM

• Our data suggest that high levels of KSPG expression correlate to a downregulated immunophenotype of resident macrophages in the nervous system [8].
• The protein shows highest identity (36%) to fibromodulin and 33% to bovine lumican, two other leucine-rich repeat connective tissue proteins [10].
• Unlike the other proteoglycans, lumican could not be detected throughout the growth plate [11].
• Differential distribution of lumican and fibromodulin in tooth cementum [12].
• This dual interaction displayed by KSPG with collagen and with lipid assemblages suggests that it plays the role of a 'filler' in the extracellular matrix of the cornea [13].

Associations of LUM with chemical compounds

• About two-thirds of the lumican protein consists of a series of 10 amino acid leucine-rich repeats that occur in regions of calculated high beta-hydrophobic moment, suggesting that the leucine-rich repeats contribute to beta-sheet formation in these proteins [6].
• Location of 6 cysteine and 4 consensus N-glycosylation sites in the bovine sequence were identical to those in chicken lumican [6].
• Cells in control corneas synthesized both a chondroitin sulfate proteoglycan and a keratan sulfate proteoglycan similar to those present in monkey and bovine corneas [1].
• Treatment of arterial lumican with endo-beta-galactosidase released 8-9 mol of glucosamine and galactose per mol of protein as oligosaccharides [14].
• These results show that cultured bovine keratocytes maintain the ability to express all three of the known KSPG proteins, modified with keratan sulfate chains and sulfated on both N-acetylglucosamine and galactose moieties [15].

Physical interactions of LUM

• Osteoadherin is a cell binding keratan sulfate proteoglycan which was recently isolated from mineralized bovine bone and subsequently cloned and sequenced [16].

Other interactions of LUM

• Keratocan, like lumican, is a core protein of a major corneal proteoglycan but is present in non-corneal tissues primarily as a nonsulfated glycoprotein [9].
• We conclude that the full-length translation product of the gene producing osteoglycin is a corneal keratan sulfate proteoglycan, also present in many non-corneal tissues without keratan sulfate chains [17].
• The small proteoglycans, decorin, fibromodulin, biglycan, and lumican, represent a family of structurally related but genetically distinct molecules present in many types of connective tissues [18].
• By comparison with aggrecan, the small leucine-rich repeat proteoglycans decorin, biglycan and lumican showed a resistance to both proteolytic cleavage and release throughout the culture period [19].

Analytical, diagnostic and therapeutic context of LUM

• Bovine cornea contains three unique keratan sulfate proteoglycans (KSPGs), of which two (lumican and keratocan) have been characterized using molecular cloning [17].
• A glycoprotein reactive with antibodies against corneal keratan sulfate proteoglycan (KSPG) was purified 300-fold from extracts of bovine aorta using DEAE ion-exchange, gel-filtration, hydrophobic interaction, and reverse-phase chromatographic separations [14].
• Previous studies have been able to show only transient secretion of KSPG in cell culture [15].
• Keratan sulfate and core protein antigens co-eluted with purified corneal keratan sulfate proteoglycan on ion exchange high-performance liquid chromatography (HPLC) [20].
• Northern hybridization and immunoblotting of tissue extracts found keratocan distribution to be more limited than that of lumican or fibromodulin [9].

References