Transcriptional repression of the c-fos gene by YY1 is mediated by a direct interaction with ATF/CREB.
Transcriptional activation of the mouse c-fos gene by the adenovirus 243-amino-acid E1A protein requires a binding site for transcription factor YY1 located at -54 of the c-fos promoter. YY1 normally represses transcription of c-fos, and this repression depends on the presence of a cyclic AMP (cAMP) response element located immediately ... upstream of the -54 YY1 DNA-binding site. This finding suggested that the mechanism of transcriptional repression by YY1 might involve a direct interaction with members of the ATF/CREB family of transcription factors. In vitro and in vivo binding assays were used to demonstrate that YY1 can interact with ATF/CREB proteins, including CREB, ATF-2, ATFa1, ATFa2, and ATFa3. Structure-function analyses of YY1 and ATFa2 revealed that the C-terminal zinc finger domain of YY1 is necessary and sufficient for binding to ATFa2 and that the basic-leucine zipper region of ATFa2 is necessary and sufficient for binding to YY1. Overexpression of YY1 in HeLa cells resulted in repression of a mutant c-fos chloramphenicol acetyltransferase reporter that lacked binding sites for YY1, suggesting that repression can be triggered through protein-protein interactions with ATF/CREB family members. Consistent with this finding, repression was relieved upon removal of the upstream cAMP response element. These data support a model in which YY1 binds simultaneously to its own DNA-binding site in the c-fos promoter and also to adjacent DNA-bound ATF/CREB proteins in order to effect repression. They further suggest that the ATF/CREB-YY1 complex serves as a target for the adenovirus 243-amino-acid E1A protein.
Mesh Terms:
Activating Transcription Factor 2, Base Sequence, Basic-Leucine Zipper Transcription Factors, Cyclic AMP Response Element-Binding Protein, DNA, DNA-Binding Proteins, Erythroid-Specific DNA-Binding Factors, G-Box Binding Factors, Genes, fos, HeLa Cells, Humans, Molecular Sequence Data, Promoter Regions, Genetic, Repressor Proteins, Structure-Activity Relationship, Transcription Factors, YY1 Transcription Factor, Zinc Fingers
Activating Transcription Factor 2, Base Sequence, Basic-Leucine Zipper Transcription Factors, Cyclic AMP Response Element-Binding Protein, DNA, DNA-Binding Proteins, Erythroid-Specific DNA-Binding Factors, G-Box Binding Factors, Genes, fos, HeLa Cells, Humans, Molecular Sequence Data, Promoter Regions, Genetic, Repressor Proteins, Structure-Activity Relationship, Transcription Factors, YY1 Transcription Factor, Zinc Fingers
J. Virol.
Date: Jul. 01, 1995
PubMed ID: 7769693
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