Identification of human GATA-2 gene distal IS exon and its expression in hematopoietic stem cell fractions

Transcription factor GATA-2 is essential for the proper function of hematop oietic stem cells and progenitors. Two first exons/promoters have been foun d in the mouse GATA-2 gene, and a distal IS promoter shows activity specifi c to hematopoietic progenitors and neural tissues. To ascertain whether the two-promoter system is also utilized in the human GATA-2 gene, we isolated and analyzed a PI phage clone containing this gene. The nucleotide sequenc e of the human GATA-2 gene 5' flanking region was determined over 10 kbp, a nd a human IS exon was identified in the locus through sequence comparison analysis with that of the mouse GATA-2 IS exon, RNA blotting and reverse-tr anscribed PCR analyses identified a transcript that starts from the IS exon in human leukemia-derived cell lines. The IS-originated transcript was als o identified in CD34-positive bone marrow and cord blood mononuclear cells, which are recognized as clinically important hematopoietic stem cell-enric hed fractions, Phylogenic comparison of the human and mouse GATA-2 gene seq uences revealed several regions in the locus that exhibit high sequence sim ilarity, These results demonstrate that the GATA-8 gene regulatory machiner y is conserved among vertebrates. The fact that the human IS promoter is ac tive in the hematopoietic stem cell/progenitor fraction may be an important clue for the design of a vector system that can specifically express vario us genes in hematopoietic stem cells and progenitors.