Transcription of the transforming growth factor-beta2 gene is dependent on an E-box located between an essential cAMP response element/activating transcription factor motif and the TATA box of the gene.
Transforming growth factor-beta2 (TGF-beta2) is an important regulator of cell proliferation and differentiation; however, its transcriptional regulation is not well understood. Here we report characterization of an essential E-box motif, positioned at -50/-45 between a previously described functional cAMP response element/activating transcription factor site and the TATA box of the human TGF-beta2 promoter. By site-directed mutagenesis, we demonstrate that this E-box motif is necessary for the promoter activity, not only in differentiated cells derived from embryonal carcinoma cells, but also in choriocarcinoma cells and in MCF-7 breast carcinoma cells. We also demonstrate that the transcription factors USF1 and USF2 bind to this E-box motif in vitro when nuclear extracts from each of these cell lines are examined by gel retardation assays. Moreover, using a dominant-negative USF2 protein, we show that USF proteins are critical for TGF-beta2 promoter activity in vivo. The importance of the E-box motif described in this study is supported by the presence of an E-box motif in the same position in the chicken TGF-beta2 gene promoter.
Scholtz
B
B
Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, Nebraska 68198-6805, USA. arizzino@unmc.edu
Kingsley-Kallesen
M
M
Rizzino
A
A
D002460:Cell Line; D017362:Cyclic AMP Response Element-Binding Protein / Q000235:genetics*; D004268:DNA-Binding Proteins; D004591:Electrophoresis, Polyacrylamide Gel; D018257:Helix-Loop-Helix Motifs; D006801:Humans; D009690:Nucleic Acid Conformation; D016385:TATA Box; D014157:Transcription Factors / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000235:genetics*; D014407:Tumor Cells, Cultured; D051720:Upstream Stimulatory Factors
D017362:Cyclic AMP Response Element-Binding Protein; D004268:DNA-Binding Proteins; D014157:Transcription Factors; D016212:Transforming Growth Factor beta; C497181:USF1 protein, human; C497184:USF2 protein, human; D051720:Upstream Stimulatory Factors