title: Sp1 and Sp3 transcription factors mediate interleukin-1 beta down-regulation of human type II collagen gene expression in articular chondrocytes.
abstract: Interleukin-1 beta (IL-1 beta) is a pleiotropic cytokine that was shown to inhibit the biosynthesis of articular cartilage components. Here we demonstrate that IL-1 beta inhibits the production of newly synthesized collagens in proliferating rabbit articular chondrocytes and that this effect is accompanied by a decrease in the steady-state levels of type II collagen mRNA. IL-1 beta down-regulates COL2A1 gene transcription through a -41/-33 bp sequence that binds a multimeric complex including Sp1 and Sp3 transcription factors. Specificity of IL-1 beta effects on COL2A1 promoter activity was demonstrated in experiments in which transfection of a wild type -50/+1 sequence of COL2A1 promoter as a decoy oligonucleotide abolished the IL-1 beta inhibition of a -63/+47 COL2A1-mediated transcription. By contrast, transfection of the related oligonucleotide harboring a targeted mutation in the -41/-33 sequence did not modify the negative effect the cytokine. Because we demonstrated previously that Sp1 was a strong activator of COL2A1 gene expression via the -63/+1 promoter region, whereas Sp3 overexpression blocked Sp1-induced promoter activity and inhibited COL2A1 gene transcription, we conclude that IL-1 beta down-regulation of that gene, as we found previously for transforming growth factor-beta 1, is mediated by an increase in the Sp3/Sp1 ratio. Moreover, IL-1 beta increased steady-state levels of Sp1 and Sp3 mRNAs, whereas it enhanced Sp3 protein expression and inhibited Sp1 protein biosynthesis. Nevertheless, IL-1 beta decreased the binding activity of both Sp1 and Sp3 to the 63-bp short COL2A1 promoter, suggesting that the cytokine exerts a post-transcriptional regulatory mechanism on Sp1 and Sp3 gene expressions. Altogether, these data indicate that modulation of Sp3/Sp1 ratio in cartilage could be a potential target to prevent or limit the tissue degradation.
authors.affiliation: Laboratoire de Biochimie du Tissu Conjonctif, Faculté de Médecine, CHU Niveau 3, Avenue de la Côte de Nacre, Caen Cedex 14032, France.
authors.forename: Christos
authors.initials: C
authors.lastname: Chadjichristos
authors.forename: Chafik
authors.initials: C
authors.lastname: Ghayor
authors.forename: Magdalini
authors.initials: M
authors.lastname: Kypriotou
authors.forename: Grégoire
authors.initials: G
authors.lastname: Martin
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Renard
authors.forename: Leena
authors.initials: L
authors.lastname: Ala-Kokko
authors.forename: Gunthram
authors.initials: G
authors.lastname: Suske
authors.forename: Benoit
authors.initials: B
authors.lastname: de Crombrugghe
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Pujol
authors.forename: Philippe
authors.initials: P
authors.lastname: Galéra
mesh_terms: D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002358:Cartilage, Articular / Q000187:drug effects / Q000378:metabolism; D002478:Cells, Cultured; D019902:Chondrocytes / Q000187:drug effects / Q000378:metabolism; D024043:Collagen Type II / Q000235:genetics*; D004247:DNA / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D015536:Down-Regulation / Q000187:drug effects; D006801:Humans; D007375:Interleukin-1 / Q000494:pharmacology*; D016297:Mutagenesis, Site-Directed; D016328:NF-kappa B / Q000378:metabolism; D011401:Promoter Regions, Genetic; D012323:RNA Processing, Post-Transcriptional / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011817:Rabbits; D011994:Recombinant Proteins / Q000494:pharmacology; D016329:Sp1 Transcription Factor / Q000235:genetics / Q000378:metabolism*; D051705:Sp3 Transcription Factor; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: C499177:COL2A1 protein, human; D024043:Collagen Type II; D004268:DNA-Binding Proteins; D007375:Interleukin-1; D016328:NF-kappa B; D012333:RNA, Messenger; D011994:Recombinant Proteins; C497121:SP3 protein, human; D016329:Sp1 Transcription Factor; D014157:Transcription Factors; D051705:Sp3 Transcription Factor; D004247:DNA