Functional characterization of the promoter for the gene encoding murine CD34

Since CD34 expression is restricted to the hematopoietic stem cells and decreases in differentiating cells, the analysis of the CD34 promoter is of interest to understand regulation of gene expression in stem cells. To characterize the cis-acting elements which control murine CD34 (mCD34) gene expression, we sought to clone, sequence, and functionally analyze the mCD34 promoter. An 80% decrease in promoter activity was obtained when sequences between -119 bp and -59 bp upstream of the transcriptional start site were deleted. We identified several DNA-protein complexes which correspond to functional segments defined by the linker-scanning mutants. These findings indicated the presence of the important regulatory element between bp -119 and -100, GGTTAAAAGTGAAGTAGGAA. Furthermore, from the result of functional promoter analysis in the DNase I hypersensitive site (HS) located within 5 kb upstream of the mCD34 gene, the presence of the enhancer region in the NcoI/PstI fragment of 5' upstream, -2.8 kb to -1.9 kb, has been identified. These data will provide useful information on the gene transfer using the CD34 promoter and enhancer.