Sox9, a key transcription factor of bone morphogenetic protein-2-induced chondrogenesis, is activated through BMP pathway and a CCAAT box in the proximal promoter.
Mouse embryonic fibroblasts (MEFs) can be differentiated into fully functional chondrocytes in response to bone morphogenetic protein-2 (BMP-2). The expression of Sox9, a critical transcription factor for the multiple steps of chondrogenesis, has been reported to be upregulated during this process. But the molecular mechanisms by which BMP-2 promotes chondrogenesis still remain largely unknown. The aim of the present study was therefore to investigate the underlying mechanism. In the MEFs, BMP-2 efficiently induced Sox9 expression along with chondrogenic differentiation in a time- and dose-dependent manner. SB203580, a specific inhibitor for p38 pathway, blocked BMP-2-induced chondrogenic differentiation as well as Sox9 expression and its transactivation of downstream genes. Forced expression of Smad6, a natural antagonist for BMP/Smad pathway, only inhibited Sox9 protein function without rendering any effects on its mRNA expression. A CCAAT box was identified in Sox9 promoter as the cis-elements responsible for BMP-2 stimulation. This study provides insight into the mechanisms underlying BMP-2-regulated Sox9 expression and activity in MEFs, and suggests differential roles of BMP-2/p38 and BMP-2/Smad pathways in modulating the function of Sox9 during chondrogenesis.
Pan
Qiuhui
Q
Medical Research Center, the Second Affiliated Hospital, Sun Yat-sen University, Guangzhou City, Guangdong Province, PR China.
Yu
Yongchun
Y
Chen
Qiongyu
Q
Li
Chunsheng
C
Wu
Hong
H
Wan
Yang
Y
Ma
Ji
J
Sun
Fenyong
F
D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins / Q000378:metabolism*; D002454:Cell Differentiation / Q000502:physiology; D002478:Cells, Cultured; D002645:Chickens; D020219:Chondrogenesis / Q000502:physiology*; D024202:Electrophoretic Mobility Shift Assay; D004789:Enzyme Activation / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005347:Fibroblasts / Q000166:cytology*; D005786:Gene Expression Regulation; D006609:High Mobility Group Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D020133:Reverse Transcriptase Polymerase Chain Reaction; D055758:SOX9 Transcription Factor; D012689:Sequence Homology, Nucleic Acid; D051905:Smad6 Protein / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014162:Transfection; D016212:Transforming Growth Factor beta / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases / Q000187:drug effects / Q000378:metabolism
C525718:BMP2 protein, human; C525719:Bmp2 protein, mouse; C525720:Bmp2 protein, rat; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins; D004791:Enzyme Inhibitors; D006609:High Mobility Group Proteins; D055758:SOX9 Transcription Factor; C527932:SOX9 protein, human; D051905:Smad6 Protein; C497804:Smad6 protein, rat; C527933:Sox9 protein, mouse; D014157:Transcription Factors; D016212:Transforming Growth Factor beta; D048051:p38 Mitogen-Activated Protein Kinases