Regulation of xylosyltransferase I gene expression by interleukin 1beta in human primary chondrocyte cells: mechanism and impact on proteoglycan synthesis.
Fiche publication
Date publication
janvier 2013
Auteurs
Membres identifiés du Cancéropôle Est :
Dr FOURNEL-GIGLEUX Sylvie, Pr MAGDALOU Jacques, Dr OUZZINE Mohamed
Tous les auteurs :
Khair M, Bourhim M, Barre L, Li D, Netter P, Magdalou J, Fournel-Gigleux S, Ouzzine M
Lien Pubmed
Résumé
Xylosyltransferase I (XT-I) is an essential enzyme of proteoglycan (PG) biosynthesis pathway catalyzing the initial and rate-limiting step in glycosaminoglycan chain assembly. It plays a critical role in the regulation of PG synthesis in cartilage; however, little is known about underlying mechanism. Here, we provide evidence that, in human primary chondrocytes, IL-1beta regulates XT-I gene expression into an early phase of induction and a late phase of down-regulation. Based on promoter deletions, the region up to -850 bp was defined as a major element of XT-I gene displaying both constitutive and IL-1beta-regulated promoter activity. Point mutation and signaling analyses revealed that IL-1beta-induced promoter activity is achieved through AP-1 response elements and mediated by SAP/JNK and p38 signaling pathways. Transactivation and chromatin immunoprecipitation assays indicated that AP-1 is a potent transactivator of XT-I promoter and that IL-1beta-induced activity is mediated through increased recruitment of AP-1 to the promoter. Finally, we show that Sp3 is a repressor of XT-I promoter and bring evidence that the repressive effect of IL-1beta during the late phase is mediated through Sp3 recruitment to the promoter. This suggests that modulation of Sp3 in cartilage could prevent IL-1beta inhibition of PG synthesis and limit tissue degradation.
Référence
J Biol Chem. 2013 Jan 18;288(3):1774-84