SOX9 is a transcription factor that activates type II procollagen (Col2a1) gene expression during chondrocyte differentiation. Glucocorticoids are also known to promote chondrocyte differentiation via unknown molecular mechanisms. We therefore investigated the effects of a synthetic glucocorticoid, dexamethasone (DEX), on Sox9 gene expression in chondrocytes prepared from rib cartilage of newborn mice. Sox9 mRNA was expressed at high levels in these chondrocytes. Treatment with DEX enhanced Sox9 mRNA expression within 24 h and this effect was observed at least up to 48 h. The effect of DEX was dose dependent, starting at 0.1 nM and maximal at 10 nM. The half life of Sox9 mRNA was approximately 45 min in the presence or absence of DEX. Western blot analysis revealed that DEX also enhanced the levels of SOX9 protein expression. Treatment with DEX enhanced Col2a1 mRNA expression in these chondrocytes and furthermore, DEX enhanced the activity of Col2-CAT (chloramphenicol acetyltransferase) construct containing a 1.6 kb intron fragment where chondrocyte-specific Sry/Sox- consensus sequence is located. The enhancing effect of DEX was specific to SOX9, as DEX did not alter the levels of Sox6 mRNA expression. These data suggest that DEX promotes chondrocyte differentiation through enhancement of SOX9.

This article has been cited by other articles:

				R. A. Oldershaw, S. R. Tew, A. M. Russell, K. Meade, R. Hawkins, T. R. McKay, K. R. Brennan, and T. E. Hardingham Notch Signaling Through Jagged-1 Is Necessary to Initiate Chondrogenesis in Human Bone Marrow Stromal Cells but Must Be Switched off to Complete Chondrogenesis Stem Cells, March 1, 2008; 26(3): 666 - 674. [Abstract] [Full Text] [PDF]

				L. K. Mathew, S. Sengupta, A. Kawakami, E. A. Andreasen, C. V. Lohr, C. A. Loynes, S. A. Renshaw, R. T. Peterson, and R. L. Tanguay Unraveling Tissue Regeneration Pathways Using Chemical Genetics J. Biol. Chem., November 30, 2007; 282(48): 35202 - 35210. [Abstract] [Full Text] [PDF]

				S. R. Tew and T. E. Hardingham Regulation of SOX9 mRNA in Human Articular Chondrocytes Involving p38 MAPK Activation and mRNA Stabilization J. Biol. Chem., December 22, 2006; 281(51): 39471 - 39479. [Abstract] [Full Text] [PDF]

				I. Sekiya, J. T. Vuoristo, B. L. Larson, and D. J. Prockop In vitro cartilage formation by human adult stem cells from bone marrow stroma defines the sequence of cellular and molecular events during chondrogenesis PNAS, April 2, 2002; 99(7): 4397 - 4402. [Abstract] [Full Text] [PDF]

				I. Sekiya, J. T. Vuoristo, B. L. Larson, and D. J. Prockop In vitro cartilage formation by human adult stem cells from bone marrow stroma defines the sequence of cellular and molecular events during chondrogenesis PNAS, April 2, 2002; 99(7): 4397 - 4402. [Abstract] [Full Text] [PDF]