Transcriptional autorepression of Msx1 gene is mediated by interactions of Msx1 protein with a multi-protein transcriptional complex containing TATA-binding protein, Sp1 and cAMP-response-element-binding protein-binding protein (CBP/p300).
The TATA-less murine Msx1 promoter contains two Msx1-binding motifs, located at -568 to -573 and +25 to +30, and is subject to potent autorepression [Takahashi, Guron, Shetty, Matsui and Raghow (1997) J. Biol. Chem. 272, 22667-22678]. To investigate the molecular mechanism by which Msx1 represses the activity of its own promoter, we transfected C2C12 myoblasts with Msx1-promoter-luciferase constructs and assessed reporter gene activity, with and without the exogenous expression of Msx1. We demonstrate that Msx1-mediated autorepression remained unaffected, regardless of the presence or absence of the Msx1 recognition motifs on the promoter. Furthermore, graded exogenous expression of TATA-binding protein (TBP), Sp1 or cAMP-response-element-binding protein-binding protein (CBP/p300) could counteract the autoinhibitory activity of Msx1. Finally, we demonstrate that Msx1 protein can be immunoprecipitated in a multiprotein complex containing TBP, Sp1 and CBP/p300. We hypothesize that the interaction of Msx1 protein with one or more ubiquitous or tissue-restricted transcription factors mediates transcriptional autorepression of the Msx1 gene.
Shetty
S
S
Department of Biology, The University of Memphis, Memphis, TN 38152, USA.
Takahashi
T
T
Matsui
H
H
Ayengar
R
R
Raghow
R
R
D000818:Animals; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D015536:Down-Regulation; D051548:Histone Acetyltransferases; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism; D051957:MSX1 Transcription Factor; D051379:Mice; D056921:Nuclear Receptor Coactivator 3; D011233:Precipitin Tests; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D020218:Response Elements / Q000235:genetics; D017384:Sequence Deletion; D016329:Sp1 Transcription Factor / Q000235:genetics / Q000378:metabolism*; D035181:TATA-Box Binding Protein; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic / Q000235:genetics; D014162:Transfection; D014407:Tumor Cells, Cultured
D004268:DNA-Binding Proteins; D018398:Homeodomain Proteins; D051957:MSX1 Transcription Factor; D012097:Repressor Proteins; D016329:Sp1 Transcription Factor; D035181:TATA-Box Binding Protein; D015534:Trans-Activators; D014157:Transcription Factors; D051548:Histone Acetyltransferases; C538867:Ncoa3 protein, mouse; D056921:Nuclear Receptor Coactivator 3