title: Chondroitin sulfate synthase-2 is necessary for chain extension of chondroitin sulfate but not critical for skeletal development.
abstract: Chondroitin sulfate (CS) is a linear polysaccharide consisting of repeating disaccharide units of N-acetyl-D-galactosamine and D-glucuronic acid residues, modified with sulfated residues at various positions. Based on its structural diversity in chain length and sulfation patterns, CS provides specific biological functions in cell adhesion, morphogenesis, neural network formation, and cell division. To date, six glycosyltransferases are known to be involved in the biosynthesis of chondroitin saccharide chains, and a hetero-oligomer complex of chondroitin sulfate synthase-1 (CSS1)/chondroitin synthase-1 and chondroitin sulfate synthase-2 (CSS2)/chondroitin polymerizing factor is known to have the strongest polymerizing activity. Here, we generated and analyzed CSS2(-/-) mice. Although they were viable and fertile, exhibiting no overt morphological abnormalities or osteoarthritis, their cartilage contained CS chains with a shorter length and at a similar number to wild type. Further analysis using CSS2(-/-) chondrocyte culture systems, together with siRNA of CSS1, revealed the presence of two CS chain species in length, suggesting two steps of CS chain polymerization; i.e., elongation from the linkage region up to Mr ∼10,000, and further extension. There, CSS2 mainly participated in the extension, whereas CSS1 participated in both the extension and the initiation. Our study demonstrates the distinct function of CSS1 and CSS2, providing a clue in the elucidation of the mechanism of CS biosynthesis.
authors.affiliation: Institute for Molecular Science of Medicine, Aichi Medical University, Nagakute, Japan.
authors.forename: Hiroyasu
authors.initials: H
authors.lastname: Ogawa
authors.forename: Sonoko
authors.initials: S
authors.lastname: Hatano
authors.forename: Nobuo
authors.initials: N
authors.lastname: Sugiura
authors.forename: Naoko
authors.initials: N
authors.lastname: Nagai
authors.forename: Takashi
authors.initials: T
authors.lastname: Sato
authors.forename: Katsuji
authors.initials: K
authors.lastname: Shimizu
authors.forename: Koji
authors.initials: K
authors.lastname: Kimata
authors.forename: Hisashi
authors.initials: H
authors.lastname: Narimatsu
authors.forename: Hideto
authors.initials: H
authors.lastname: Watanabe
mesh_terms: D000818:Animals; D001846:Bone Development; D002809:Chondroitin Sulfates / Q000096:biosynthesis* / Q000737:chemistry*; D005260:Female; D015971:Gene Expression Regulation, Enzymologic; D014453:Glucuronosyltransferase; D016695:Glycosyltransferases / Q000378:metabolism; D006602:Hexosyltransferases / Q000172:deficiency / Q000378:metabolism*; D008297:Male; D051379:Mice; D064251:Multifunctional Enzymes; D017350:N-Acetylgalactosaminyltransferases
chemical_list: D064251:Multifunctional Enzymes; D002809:Chondroitin Sulfates; D016695:Glycosyltransferases; D006602:Hexosyltransferases; D017350:N-Acetylgalactosaminyltransferases; C477294:chondroitin sulfate synthase-2; D014453:Glucuronosyltransferase; C571290:Chsy1 protein, mouse