Transcriptional suppression of Sox9 expression in chondrocytes by retinoic acid

• Published in: Journal of cellular biochemistry Vol. 81; no. S36; pp. 71 - 78
• Main Authors: Sekiya, Ichiro, Koopman, Peter, Tsuji, Kunikazu, Mertin, Sabine, Harley, Vincent, Yamada, Yoshihiko, Shinomiya, Kenichi, Niguji, Akira, Noda, Masaki
• Format: Journal Article
• Language: English
• Published: New York John Wiley & Sons, Inc 2001
• Subjects: Animals; Blotting, Northern; Blotting, Western; Cells, Cultured; chondrocyte; Chondrocytes - metabolism; Down-Regulation; Enhancer Elements, Genetic; High Mobility Group Proteins - genetics; High Mobility Group Proteins - metabolism; Mice; Mice, Inbred ICR; retinoic acid; RNA, Messenger - metabolism; SOX9; SOX9 Transcription Factor; transcription; Transcription Factors - genetics; Transcription Factors - metabolism; Transcription, Genetic; Tretinoin - metabolism; Tretinoin - pharmacology; type II collagen
• ISSN: 0730-2312; 0733-1959; 1097-4644
• DOI: 10.1002/jcb.1077

SOX9 is a transcription factor that is expressed in chondrocytes and regulates expression of chondrocyte phenotype related genes. Expression of these genes is known to be suppressed by retinoic acid (RA). We, therefore, examined whether the Sox9 gene expression is regulated by RA in chondrocytes. RA treatment suppressed Sox9 mRNA expression in primary chondrocytes prepared from newborn mouse rib cartilage within 12 h and this suppression lasted at least up to 24 h. The RA suppression of Sox9 mRNA levels was dose‐dependent starting at 0.5 μM with a maximum at 1 μM. Nuclear run‐on assays revealed that RA reduced the rate of transcription of Sox9 gene. Finally, Western blot analysis indicated that RA suppressed SOX9 protein levels in these chondrocytes. Furthermore, overexpression of SOX9 reversed RA suppression of Col2a1 enhancer activity. These observations indicate that RA suppresses Sox9 gene expression in chondrocytes at least in part through transcriptional events. J. Cell. Biochem. Suppl. 36: 71–78, 2001. © 2001 Wiley‐Liss, Inc.