FUNCTIONAL INTERACTION OF GATA1 WITH ERYTHROID KRUPPEL-LIKE FACTOR AND SP1 AT DEFINED ERYTHROID PROMOTERS

GATA and CACC elements commonly are codistributed within the regulator y domains of a variety of erythroid genes. Using Drosophila S2 cells, the actions of GATA1, Sp1, and erythroid Kruppel-like factor (EKLF) at these elements within model erythroid promoters have been assessed. F or each promoter studied (erythroid pyruvate kinase, glycophorin B, an d a murine beta(maj) globin-derived construct, GCT) Sp1 and EKLF each activated transcription despite differences in CACC element sequence, orientation, and positioning. However, GATA1 acted in apparent coopera tivity with Spl at the pyruvate kinase promoter; with EKLF at the beta (maj) globin-derived GCT promoter; and with either Spl or EKLF at the glycophorin B promoter. Thus, GATA1 may functionally interact with eac h of these Kruppel-like factors depending on promoter context; and at the GCT promoter, transcriptional activation by GATA1 and EKLF was gre ater than or equal to 10-fold higher than levels attributable to addit ive effects. The possibility that interactions between these activator s may be direct was supported by the specific binding of baculoviral-e xpressed EKLF to GATA1. This report underlines the likelihood that dis crete roles exist for Sp1 and EKLF in erythroid gene activation. and s upports a mechanism of direct cooperativity for EKLF and GATA1 as core gulators. (C) 1996 by The American Society of Hematology.