title: Xylosyltransferase-I regulates glycosaminoglycan synthesis during the pathogenic process of human osteoarthritis.
abstract: Loss of glycosaminoglycan (GAG) chains of proteoglycans (PGs) is an early event of osteoarthritis (OA) resulting in cartilage degradation that has been previously demonstrated in both huma and experimental OA models. However, the mechanism of GAG loss and the role of xylosyltransferase-I (XT-I) that initiates GAG biosynthesis onto PG molecules in the pathogenic process of human OA are unknown. In this study, we have characterized XT-I expression and activity together with GAG synthesis in human OA cartilage obtained from different regions of the same joint, defined as "normal", "late-stage" or adjacent to "late-stage". The results showed that GAG synthesis and content increased in cartilage from areas flanking OA lesions compared to cartilage from macroscopically "normal" unaffected regions, while decreased in "late-stage" OA cartilage lesions. This increase in anabolic state was associated with a marked upregulation of XT-I expression and activity in cartilage "next to lesion" while a decrease in the "late-stage" OA cartilage. Importantly, XT-I inhibition by shRNA or forced-expression with a pCMV-XT-I construct correlated with the modulation of GAG anabolism in human cartilage explants. The observation that XT-I gene expression was down-regulated by IL-1β and up-regulated by TGF-β1 indicates that these cytokines may play a role in regulating GAG content in human OA. Noteworthy, expression of IL-1β receptor (IL-1R1) was down-regulated whereas that of TGF-β1 was up-regulated in early OA cartilage. Theses observations may account for upregulation of XT-I and sustained GAG synthesis prior to the development of cartilage lesions during the pathogenic process of OA.
authors.affiliation: UMR 7561 CNRS-Université Nancy 1, Faculté de Médecine, Vandœuvre-lès-Nancy, France.
authors.forename: Narayanan
authors.initials: N
authors.lastname: Venkatesan
authors.forename: Lydia
authors.initials: L
authors.lastname: Barré
authors.forename: Mustapha
authors.initials: M
authors.lastname: Bourhim
authors.forename: Jacques
authors.initials: J
authors.lastname: Magdalou
authors.forename: Didier
authors.initials: D
authors.lastname: Mainard
authors.forename: Patrick
authors.initials: P
authors.lastname: Netter
authors.forename: Sylvie
authors.initials: S
authors.lastname: Fournel-Gigleux
authors.forename: Mohamed
authors.initials: M
authors.lastname: Ouzzine
mesh_terms: D000368:Aged; D002358:Cartilage, Articular / Q000378:metabolism; D018450:Disease Progression; D005269:Femur / Q000473:pathology; D020869:Gene Expression Profiling; D015971:Gene Expression Regulation, Enzymologic; D006025:Glycosaminoglycans / Q000378:metabolism*; D006801:Humans; D053583:Interleukin-1beta / Q000378:metabolism; D008875:Middle Aged; D008954:Models, Biological; D010003:Osteoarthritis / Q000378:metabolism*; D010430:Pentosyltransferases / Q000502:physiology*; D053573:Receptors, Interleukin-1 Type I / Q000378:metabolism*; D053773:Transforming Growth Factor beta1 / Q000378:metabolism; D000097608:UDP Xylose-Protein Xylosyltransferase
chemical_list: D006025:Glycosaminoglycans; D053583:Interleukin-1beta; D010430:Pentosyltransferases; D053573:Receptors, Interleukin-1 Type I; D053773:Transforming Growth Factor beta1; D000097608:UDP Xylose-Protein Xylosyltransferase; C508590:IL1R1 protein, human