Synergistic transcriptional activation by hGABP and select members of the activation transcription factor/cAMP response element-binding protein family.
The Ets-related DNA-binding protein human GA-binding protein (hGABP) alpha interacts with the four ankyrin-type repeats of hGABPbeta to form an hGABP tetrameric complex that stimulates transcription through the adenovirus early 4 (E4) promoter. Using co-transfection assays, this study demonstrated that the hGABP complex mediated efficient activation of transcription from E4 promoter synergistically with activating transcription factor (ATF) 1 or cAMP response element-binding protein (CREB), but not ATF2/CRE-BP1. This synergy also partially occurred when hGABPalpha was used alone in place of the combination of hGABPalpha and hGABPbeta. hGABP activated an artificial promoter containing only ATF/CREB-binding sites under coexistence of ATF1 or CREB. Consistent with these results, physical interactions of hGABPalpha with ATF1 or CREB were observed in vitro. Functional domain analyses of the physical interactions revealed that the amino-terminal region of hGABPalpha bound to the DNA-binding domain of ATF1, which resulted in the formation of ternary complexes composed of ATF1, hGABPalpha, and hGABPbeta. In contrast to hGABPalpha, hGABPbeta did not significantly interact with ATF1 and CREB. Taken together, these results indicate that hGABP functionally interacts with selective members of the ATF/CREB family, and also suggest that synergy results from multiple interactions which mediate stabilization of large complexes within the regulatory elements of the promoter region, including DNA-binding and non-DNA-binding factors.
Sawada
J
J
Research Function for Biotechnology, Frontier Collaborative Research Center, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8501, Japan.
Simizu
N
N
Suzuki
F
F
Sawa
C
C
Goto
M
M
Hasegawa
M
M
Imai
T
T
Watanabe
H
H
Handa
H
H
D051697:Activating Transcription Factor 1; D051698:Activating Transcription Factor 2; D000256:Adenoviridae / Q000235:genetics*; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004331:Drosophila melanogaster; D051268:GA-Binding Protein Transcription Factor; D006367:HeLa Cells; D006801:Humans; D007700:Kinetics; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014162:Transfection
C497105:ATF2 protein, human; D051697:Activating Transcription Factor 1; D051698:Activating Transcription Factor 2; D017362:Cyclic AMP Response Element-Binding Protein; D004268:DNA-Binding Proteins; D051268:GA-Binding Protein Transcription Factor; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors