AP-1 and Cbfa/runt physically interact and regulate parathyroid hormone-dependent MMP13 expression in osteoblasts through a new osteoblast-specific element 2/AP-1 composite element.
The expression of MMP13 (collagenase-3), a member of the matrix metalloproteinase family, is increased in vivo as well as in cultured osteosarcoma cell lines by parathyroid hormone (PTH), a major regulator of calcium homeostasis. Binding sites for AP-1 and Cbfa/Runt transcription factors in close proximity have been identified as cis-acting elements in the murine and rat mmp13 promoter required for PTH-induced expression. The cooperative function of these factors in response to PTH in osteoblastic cells suggests a direct interaction between AP-1 and Cbfa/Runt transcription factors. Here, we demonstrate interaction between c-Jun and c-Fos with Cbfa/Runt proteins. This interaction depends on the leucine zipper of c-Jun or c-Fos and the Runt domain of Cbfa/Runt proteins, respectively. Moreover, c-Fos interacts with the C-terminal part of Cbfa1 and Cbfa2, sharing a conserved transcriptional repression domain. In addition to the distal osteoblast-specific element 2 (OSE2) element in the murine and rat mmp13 promoter, we identified a new proximal OSE2 site overlapping with the TRE motif. Both interaction of Cbfa/Runt proteins with AP-1 and the presence of a functional proximal OSE2 site are required for enhanced transcriptional activity of the mmp13 promoter in transient transfected fibroblasts and in PTH-treated osteosarcoma cells.
Deutsches Krebsforschungszentrum Heidelberg, Division of Signal Transduction and Growth Control (B0800), Im Neuenheimer Feld 280, D-69120 Heidelberg, Germany.
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Hess
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Munz
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Angel
D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D017364:Collagenases / Q000378:metabolism*; D050659:Core Binding Factor Alpha 1 Subunit; D017931:DNA Primers; D006801:Humans; D016350:Leucine Zippers; D053509:Matrix Metalloproteinase 13; D051379:Mice; D009363:Neoplasm Proteins; D010006:Osteoblasts / Q000201:enzymology*; D010281:Parathyroid Hormone / Q000378:metabolism*; D011485:Protein Binding; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D018808:Transcription Factor AP-1 / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*
D050659:Core Binding Factor Alpha 1 Subunit; D017931:DNA Primers; D009363:Neoplasm Proteins; D010281:Parathyroid Hormone; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D011994:Recombinant Proteins; D018808:Transcription Factor AP-1; D014157:Transcription Factors; D017364:Collagenases; C507079:MMP13 protein, human; D053509:Matrix Metalloproteinase 13; C507081:Mmp13 protein, mouse; C507083:Mmp13 protein, rat; D013755:Tetradecanoylphorbol Acetate