Serum-inducible factors binding to an activating transcription factor motif regulate transcription of the Id2A promoter during myogenic differentiation.
Expression of Id, a dominant negative regulator of helix-loop-helix transcription factors, is tightly regulated during cellular differentiation. In this study, we have defined the sequences responsible for the transcriptional regulation of the human Id2A gene. 5' deletion and site-specific mutation analyses of the Id2A promoter showed that both an Sp-1 site and an activating transcription factor (ATF)-like site (referred to as IdATF sites) are required for expression in C2 cells, whereas these sites are not essential for the expression in nonmuscle cells, including HeLa and 10T1/2 cells. Gel shift assays revealed nuclear factors with specific binding to IdATF sites in both C2 and HeLa cells, which are efficiently competed by either legitimate ATF- or AP-1 binding sites. DNA binding activity to IdATF sites was clearly decreased during C2 cell differentiation and rapidly reactivated by treatment with either phorbol 12-myristate 13-acetate or serum, which correlated with the induction of endogenous Id2A mRNA expression. In addition, we show that overexpression of the catalytic domain of protein kinase C leads to the activation of the Id2A promoter through IdATF sites in C2 cells. These results suggest a model in which down-modulation of IdATF site binding activity by mitogen depletion contributes to the down-regulation of Id2A gene expression that is essential for myogenic differentiation.
Kurabayashi
M
M
Department of Biochemistry and Molecular Biology, University of Southern California School of Medicine, Los Angeles 90033.
Dutta
S
S
Kedes
L
L
D001483:Base Sequence; D001769:Blood; D002454:Cell Differentiation / Q000235:genetics*; D002478:Cells, Cultured; D015536:Down-Regulation; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D009132:Muscles / Q000166:cytology*; D016297:Mutagenesis, Site-Directed; D009838:Oligodeoxyribonucleotides; D011401:Promoter Regions, Genetic; D011493:Protein Kinase C / Q000378:metabolism; D017384:Sequence Deletion; D014157:Transcription Factors / Q000378:metabolism*
D009838:Oligodeoxyribonucleotides; D014157:Transcription Factors; D011493:Protein Kinase C