Transcriptional Co-activators CREB-binding protein/p300 increase chondrocyte Cd-rap gene expression by multiple mechanisms including sequestration of the repressor CCAAT/enhancer-binding protein.
Cartilage-derived retinoic acid-sensitive protein (CD-RAP) is a small secreted matrix protein expressed in developing and adult cartilage and by chondrocytes in culture. We have previously shown that the expression of Cd-rap, like many other cartilage matrix proteins, is repressed by interleukin 1beta and that the transcription factor CCAAT/enhancer-binding protein (C/EBP) beta plays an important role in the interleukin 1beta-induced repression (Okazaki, K., Li, J., Yu, H., Fukui, N., and Sandell, L. J. (2002) J. Biol. Chem. 277, 31526-31533). The co-activators CREB-binding protein (CBP) and p300 are transcriptional co-regulators that participate in the activities of many different transcription factors including C/EBP. Here we show that CBP/p300 can reverse the inhibitory effect of C/EBP and moreover can stimulate expression of Cd-rap. The mechanism of this effect is shown to involve a unique synergy whereby CBP/p300 stimulate Cd-rap gene expression by at least two mechanisms. First, binding of CBP/p300 to C/EBPbeta leads to sequestration of C/EBP eliminating DNA binding and subsequent repression; second, binding of CBP/p300 to the transcriptional activator Sox9 increases Sox9 DNA binding to the Cd-rap promoter leading to further stimulation of gene transcription. This is an example of a complementary transcriptional network whereby two very different mechanisms act together to confer a functional increase in transcription. This new paradigm is likely generally applicable to cartilage genes as Col2a1 cartilage collagen gene responds similarly.
Imamura
Toshihiro
T
Department of Orthopaedic Surgery, Washington University School of Medicine at Barnes-Jewish Hospital, St. Louis, Missouri 63110, USA.
Imamura
Chisako
C
Iwamoto
Yukihide
Y
Sandell
Linda J
LJ
D000818:Animals; D001665:Binding Sites; D015152:Blotting, Northern; D002356:Cartilage / Q000378:metabolism; D045744:Cell Line, Tumor; D019902:Chondrocytes / Q000378:metabolism*; D002843:Chromatin / Q000378:metabolism; D047369:Chromatin Immunoprecipitation; D003094:Collagen / Q000378:metabolism; D004247:DNA / Q000378:metabolism; D050881:E1A-Associated p300 Protein; D005982:Glutathione Transferase / Q000378:metabolism; D006609:High Mobility Group Proteins / Q000378:metabolism; D047468:Immunoprecipitation; D007375:Interleukin-1 / Q000378:metabolism; D008156:Luciferases / Q000378:metabolism; D008957:Models, Genetic; D009154:Mutation; D009687:Nuclear Proteins / Q000737:chemistry* / Q000502:physiology*; D009841:Oligonucleotides / Q000737:chemistry; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D011506:Proteins / Q000737:chemistry* / Q000502:physiology*; D051381:Rats; D055758:SOX9 Transcription Factor; D015534:Trans-Activators / Q000737:chemistry* / Q000502:physiology*; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014162:Transfection
D002843:Chromatin; D006609:High Mobility Group Proteins; D007375:Interleukin-1; C099322:Mia protein, rat; D009687:Nuclear Proteins; D009841:Oligonucleotides; D011506:Proteins; D055758:SOX9 Transcription Factor; D015534:Trans-Activators; D014157:Transcription Factors; D003094:Collagen; D004247:DNA; D008156:Luciferases; D050881:E1A-Associated p300 Protein; C494362:Ep300 protein, rat; D005982:Glutathione Transferase