Isolation, Genomic Structure, and Expression of Human Erythroid Krüppel-Like Factor (EKLF)

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Abstract
Erythroid Krüppel-like factor (EKLF) is an essential transcriptional activator that directs high-level expression of the adult β-globin promoter by binding to its CACCC element, one of a trio of highly conserved sequences present in erythroid cell-specific promoters and enhancers. This report describes the isolation and characterization of the human homolog of murine EKLF. The human EKLF transcription unit shares a number of structural properties with its murine counterpart. Human EKLF is contained within 3 kb of genomic DNA, and its coding region is interrupted by two introns whose locations are conserved with the murine gene. The three zinc fingers share >90% sequence similarity with and are predicted to bind the same target sequence as the mouse EKLF. The rest of the protein is proline-rich and retains ∼70% sequence similarity to the mouse gene. Human EKLF is expressed in bone marrow and HEL, JK1, and OCIM1 erythroleukemic cell lines but not in K562 nor in myeloid or lymphoid cell lines. These results indicate that the genomic structure and erythroid-restricted expression of EKLF are highly conserved between the murine and human homologues. Availability of human EKLF will enable initiation of studies to molecularly assess whether it is functionally compromised in those cases of β-thalassemia that contain a normal β-globin gene locus.