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Mol. Cell. Biol., May 1995, 2437-2447, Vol 15, No. 5
M Merika and SH Orkin
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 Kruppel family
factors, the ubiquitous protein Sp1 and the erythroid-restricted factor
EKLF (erythroid Kruppel- like factor), which recognize GC and/or GT/CACC
motifs. Binding sites for both GATA-1 and these Kruppel 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.
Copyright © 1995, American Society for Microbiology
Functional synergy and physical interactions of the erythroid transcription factor GATA-1 with the Kruppel family proteins Sp1 and EKLF
Division of Hematology-Oncology, Children's Hospital, Boston, Massachusetts 02115, USA.
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