HUMAN EZF, A KRUPPEL-LIKE ZINC-FINGER PROTEIN, IS EXPRESSED IN VASCULAR ENDOTHELIAL-CELLS AND CONTAINS TRANSCRIPTIONAL ACTIVATION AND REPRESSION DOMAINS

Members of the erythroid Kruppel-like factor (EKLF) multigene family c ontain three C-terminal zinc fingers, and they are typically expressed in a limited number of tissues. EKLF, the founding member, transactiv ates the beta-globin promoter by binding to the CACCC motif, EKLF is e ssential for expression of the beta-globin gene as demonstrated by gen e deletion experiments in mice. Using a DNA probe from the zinc finger region of EKLF, we cloned a cDNA encoding a member of this family fro m a human vascular endothelial cell cDNA library, Sequence analysis in dicated that our clone, hEZF is the human homologue of the recently re ported mouse EZF and GKLF. hEZF is a single-copy gene that maps to chr omosome 9q31. By gel mobility shift analysis, purified recombinant hEZ F protein bound specifically to a probe containing the CACCC core sequ ence. In co-transfection experiments, we found that sense but not anti sense hEZF decreased the activity of a reporter plasmid containing the CACCC sequence upstream of the thymidine kinase promoter by B-fold. I n contrast, EKLF increased the activity of the reporter plasmid by 3-f old., By fusing hEZF to the DNA-binding domain of GAL4, we mapped a re pression domain in hEZF to amino acids 181-388., We also found that am ino acids 91-117 of hEZF confer an activation function on the GAL4 DNA -binding domain.