title: Rhodamine B and 2-acetamido-1,3,6-tri-O-acetyl-4-deoxy-4-fluoro-D-glucopyranose (F-GlcNAc) inhibit chondroitin/dermatan and keratan sulphate synthesis by different mechanisms in bovine chondrocytes.
abstract: MPS disorders result from a deficiency or absence of glycosaminoglycan (GAG) degrading enzymes leading to an imbalance between the synthesis and degradation of GAGs and their subsequent accumulation in a range of cells. The inhibition of GAG synthesis using small chemical inhibitors has been proposed as a novel therapeutic approach to treatment. Several inhibitors have been shown to decrease heparan sulphate GAG synthesis and in this study we evaluated a novel fluorinated analog of N-acetylglucosamine (2-acetamido-1,3,6-tri-O-acetyl-4-deoxy-4-fluoro-D-glucopyranose (F-GlcNAc)) and rhodamine B for their ability to also inhibit the synthesis of chondroitin/dermatan and keratan sulphate GAGs present in bovine cartilage. Both inhibitors decreased GAG synthesis in chondrocyte monolayer culture and in cartilage chip explant culture in a dose dependent manner. Both inhibitors decreased the size of newly synthesised proteoglycans and in the case of F-GlcNAc this was due to a decrease in newly synthesised GAG chain size. Rhodamine B, however, did not affect GAG chain size, while both inhibitors decreased the amount of chondroitin/dermatan and keratan sulphate GAG equally. The expression of genes responsible for the initiation and elongation of chondroitin/dermatan sulphate and keratan sulphate GAGs were downregulated in the presence of rhodamine B but not in the presence of F-GlcNAc. Thus the 2 inhibitors appear to have differing effects on GAG synthesis, with F-GlcNAc inhibiting the epimerisation of UDP-GlcNAc to UDP-GalNAc thus decreasing the availability of monosaccharides for addition to the growing GAG chain, whereas rhodamine B is more likely to reduce the number of GAG chains. Together with previous data these 2 inhibitors are capable of non-specific inhibition of GAG synthesis, reducing the production of chondroitin/dermatan sulphate, keratan sulphate and heparan sulphate GAGs. As such they would be applicable to therapy in a range of MPS disorders.
authors.affiliation: Department of Genetics and Molecular Pathology, SA Pathology, North Adelaide, SA 5006, Australia. ainslie.derrickroberts@adelaide.edu.au
authors.forename: Ainslie L K
authors.initials: AL
authors.lastname: Derrick-Roberts
authors.forename: Wanda
authors.initials: W
authors.lastname: Marais
authors.forename: Sharon
authors.initials: S
authors.lastname: Byers
mesh_terms: D000117:Acetylglucosamine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D002356:Cartilage / Q000378:metabolism; D002417:Cattle; D019902:Chondrocytes / Q000187:drug effects* / Q000378:metabolism*; D002809:Chondroitin Sulfates / Q000096:biosynthesis; D003871:Dermatan Sulfate / Q000096:biosynthesis; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000187:drug effects; D006025:Glycosaminoglycans / Q000096:biosynthesis*; D007632:Keratan Sulfate / Q000096:biosynthesis; D009083:Mucopolysaccharidoses / Q000235:genetics / Q000378:metabolism; D011509:Proteoglycans / Q000378:metabolism; D012235:Rhodamines / Q000494:pharmacology*
chemical_list: D006025:Glycosaminoglycans; D011509:Proteoglycans; D012235:Rhodamines; C089178:2-acetamido-1,3,6-tri-O-acetyl-4-deoxy-4-fluoroglucopyranose; D003871:Dermatan Sulfate; D002809:Chondroitin Sulfates; D007632:Keratan Sulfate; C029773:rhodamine B; D000117:Acetylglucosamine