Functional synergy and physical interactions of the erythroid transcription factor GATA-1 with the Krüppel family proteins Sp1 and EKLF.
An unresolved aspect of current understanding of erythroid cell-specific gene expression relates to how a limited number of transcriptional factors cooperate to direct high-level expression mediated by cis-regulatory elements separated over large distances within globin loci. In this report, we provide evidence that GATA-1, the major erythroid transcription factor, activates transcription in a synergistic fashion with two Krüppel family factors, the ubiquitous protein Sp1 and the erythroid-restricted factor EKLF (erythroid Krüppel-like factor), which recognize GC and/or GT/CACC motifs. Binding sites for both GATA-1 and these Krüppel proteins (especially Sp1) are found in close association in the promoters and enhancers of numerous erythroid cell-expressed genes and appear to cooperate in directing their expression. We have shown that GATA-1 interacts physically with Sp1 and EKLF and that interactions are mediated through their respective DNA-binding domains. Moreover, we show that GATA-1 and Sp1 synergize from a distance in constructs designed to mimic the architecture of globin locus control regions and downstream globin promoters. Finally, the formation of GATA-1-SP1 complexes was demonstrated in vivo by the ability of Sp1 to recruit GATA-1 to a promoter in the absence of GATA-binding sites. These experiments provide the first evidence for functionally important protein-protein interactions involved in erythroid cell-specific expression and suggest a mechanism by which DNA loops between locus control regions and globin promoters (or enhancers) might be formed or stabilized.
Merika
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M
Division of Hematology-Oncology, Children's Hospital, Boston, Massachusetts 02115, USA.
Orkin
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SH
D000818:Animals; D001665:Binding Sites / Q000235:genetics; D002460:Cell Line; D004247:DNA / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004331:Drosophila melanogaster; D004912:Erythrocytes / Q000378:metabolism; D050981:Erythroid-Specific DNA-Binding Factors; D050982:GATA1 Transcription Factor; D005914:Globins / Q000235:genetics; D051741:Kruppel-Like Transcription Factors; D051379:Mice; D008957:Models, Genetic; D011401:Promoter Regions, Genetic; D016329:Sp1 Transcription Factor / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*
D004268:DNA-Binding Proteins; D050981:Erythroid-Specific DNA-Binding Factors; D050982:GATA1 Transcription Factor; C494689:Gata1 protein, mouse; D051741:Kruppel-Like Transcription Factors; D016329:Sp1 Transcription Factor; D014157:Transcription Factors; C080774:erythroid Kruppel-like factor; D005914:Globins; D004247:DNA