title: Asporin expression is highly regulated in human chondrocytes.
abstract: A significant association between a polymorphism in the D repeat of the gene encoding asporin and osteoarthritis, the most frequent of articular diseases, has been recently reported. The goal of the present study was to investigate the expression of this new class I small leucine-rich proteoglycan (SLRP) in human articular chondrocytes. First, we studied the modulation of asporin (ASPN) expression by cytokines by Western blot and reverse transcription-polymerase chain reaction. Interleukin-1β and tumor necrosis factor-α downregulated ASPN, whereas transforming growth factor-β1 (when incubated in a serum-free medium) upregulated it. Similarly to proinflammatory cytokines, chondrocyte dedifferentiation induced by a successive passages of cells was accompanied by a decreased asporin expression, whereas their redifferentiation by three-dimensional culture restored its expression. Finally, we found an important role of the transcription factor Sp1 in the regulation of ASPN expression. Sp1 ectopic expression increased ASPN mRNA level and promoter activity. In addition, using gene reporter assay and electrophoretic mobility shift assay, we showed that Sp1 mediated its effect through a region located between -473 and -140 bp upstream of the transcription start site in ASPN gene. In conclusion, this report is the first study on the regulation of asporin expression by different cytokines in human articular chondrocytes. Our data indicate that the expression of this gene is finely regulated in cartilage and suggest a major role of Sp1.
authors.affiliation: Univ Caen, EA3214 Matrice Extracellulaire et Pathologie, Caen, France.
authors.forename: Elise
authors.initials: E
authors.lastname: Duval
authors.forename: Nicolas
authors.initials: N
authors.lastname: Bigot
authors.forename: Magalie
authors.initials: M
authors.lastname: Hervieu
authors.forename: Ikuyo
authors.initials: I
authors.lastname: Kou
authors.forename: Sylvain
authors.initials: S
authors.lastname: Leclercq
authors.forename: Philippe
authors.initials: P
authors.lastname: Galéra
authors.forename: Karim
authors.initials: K
authors.lastname: Boumediene
authors.forename: Catherine
authors.initials: C
authors.lastname: Baugé
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001665:Binding Sites / Q000235:genetics; D015153:Blotting, Western; D002358:Cartilage, Articular / Q000166:cytology; D054337:Cell Dedifferentiation / Q000235:genetics; D002454:Cell Differentiation / Q000235:genetics; D002478:Cells, Cultured; D019902:Chondrocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D015536:Down-Regulation / Q000187:drug effects; D024202:Electrophoretic Mobility Shift Assay; D016326:Extracellular Matrix Proteins / Q000235:genetics* / Q000378:metabolism; D015870:Gene Expression / Q000187:drug effects / Q000235:genetics*; D006801:Humans; D053583:Interleukin-1beta / Q000494:pharmacology; D008875:Middle Aged; D061251:Primary Cell Culture; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016329:Sp1 Transcription Factor / Q000235:genetics / Q000378:metabolism; D014162:Transfection; D053773:Transforming Growth Factor beta1 / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
chemical_list: C439889:ASPN protein, human; D016326:Extracellular Matrix Proteins; D053583:Interleukin-1beta; D016329:Sp1 Transcription Factor; D053773:Transforming Growth Factor beta1; D014409:Tumor Necrosis Factor-alpha