title: Role of sox9 in growth factor regulation of articular chondrocytes.
abstract: Chondrogenic polypeptide growth factors influence articular chondrocyte functions that are required for articular cartilage repair. Sox9 is a transcription factor that regulates chondrogenesis, but its role in the growth factor regulation of chondrocyte proliferation and matrix synthesis is poorly understood. We tested the hypotheses that selected chondrogenic growth factors regulate sox9 gene expression and protein production by adult articular chondrocytes and that sox9 modulates the actions of these growth factors. To test these hypotheses, we delivered insulin-like growth factor-I (IGF-I), fibroblast growth factor-2 (FGF-2), bone morphogenetic protein-2 (BMP-2) and/or bone morphogenetic protein-7 (BMP-7), or their respective transgenes to adult bovine articular chondrocytes, and measured changes in sox9 gene expression and protein production. We then knocked down sox9 gene expression with sox9 siRNA, and measured changes in the expression of the genes encoding aggrecan and types I and II collagen, and in the production of glycosaminoglycan, collagen and DNA. We found that FGF-2 or the combination of IGF-I, BMP-2, and BMP-7 increased sox9 gene expression and protein production and that sox9 knockdown modulated growth factor actions in a complex fashion that differed both with growth factors and with chondrocyte function. The data suggest that sox9 mediates the stimulation of matrix production by the combined growth factors and the stimulation of chondrocyte proliferation by FGF-2. The mitogenic effect of the combined growth factors and the catabolic effect of FGF-2 appear to involve sox9-independent mechanisms. Control of these molecular mechanisms may contribute to the treatment of cartilage damage.
authors.affiliation: Department of Orthopaedic Surgery, Indiana University School of Medicine, Indianapolis, Indiana, 46202-5111.
authors.forename: Shuiliang
authors.initials: S
authors.lastname: Shi
authors.affiliation: Department of Orthopaedic Surgery, Indiana University School of Medicine, Indianapolis, Indiana, 46202-5111.
authors.forename: Congrong
authors.initials: C
authors.lastname: Wang
authors.affiliation: Department of Orthopaedic Surgery, Indiana University School of Medicine, Indianapolis, Indiana, 46202-5111.
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Acton
authors.affiliation: Department of Biostatistics, Indiana University School of Medicine, Indianapolis, Indiana, 46202-5111.
authors.forename: George J
authors.initials: GJ
authors.lastname: Eckert
authors.affiliation: Department of Orthopaedic Surgery, Indiana University School of Medicine, Indianapolis, Indiana, 46202-5111.|Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana, 46202-5111.
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Trippel
mesh_terms: D000818:Animals; D055396:Bone Morphogenetic Protein 2 / Q000235:genetics / Q000378:metabolism; D055419:Bone Morphogenetic Protein 7 / Q000235:genetics / Q000378:metabolism; D002358:Cartilage, Articular / Q000166:cytology* / Q000378:metabolism; D002417:Cattle; D049109:Cell Proliferation; D002478:Cells, Cultured; D019902:Chondrocytes / Q000166:cytology / Q000378:metabolism*; D016222:Fibroblast Growth Factor 2 / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation; D007334:Insulin-Like Growth Factor I / Q000235:genetics / Q000378:metabolism; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D055758:SOX9 Transcription Factor / Q000235:genetics* / Q000378:metabolism*
chemical_list: D055396:Bone Morphogenetic Protein 2; D055419:Bone Morphogenetic Protein 7; D036341:Intercellular Signaling Peptides and Proteins; D055758:SOX9 Transcription Factor; D016222:Fibroblast Growth Factor 2; D007334:Insulin-Like Growth Factor I
keywords: ARTICULAR CHONDROCYTES; GROWTH FACTORS; SMALL INHIBITORY RNA; sox9