Comparison of the gene expression repertoire in human hematopoietic progenitors and mature leukocytes led to identification of a transcript expressed in CD34+ cells and undetectable in differentiated cells. Sequencing of the cDNA (termed EHZF: early hemetopoietic zinc finger) revealed 30 zinc fingers with 96% homology to mouse Evi3, a recently identified gene associated with the retroviral integration site in AKXD-27 B-cell lymphomas. EHZF and Evi3 share high homology with the transcription cofactor OAZ, implicated in the control of olfactory epithelium and B-lymphocyte differentiation and in the bone morphogenic protein (BMP) signal transduction. Here we show that (1) EHZF expression is abundant in human CD34+ progenitors and declines rapidly during cytokine-driven differentiation; (2) significant mRNA levels are found in most acute myelogenous leukemias; (3) in response to BMPs EHZF complexes SMADs 1 and 4, binds to, and enhances the transcriptional activity of, a BMP2/4 responsive element; (4) EHZF inhibits the transcriptional activity of early B-cell factor (EBF), a transcription factor essential for specification of the B-cell lineage. Taken together, our data suggest that EHZF is likely to play a relevant role in the control of human hematopoiesis and might be implicated in the development of hematopoietic malignancies.
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