Identification of PU.1 and Sp1 as essential transcriptional factors for the promoter activity of mouse Tec gene

Tec is a cytoplasmic protein-tyrosine kinase abundantly expressed in hematopoietic precursor cells. To investigate the mechanism regulating the expression of Tec molecule, we cloned and analysed 5' flanking region of mouse tec gene up to -2kb from the transcriptional initiation site. Luciferase assays using successive deletion mutants demonstrated that regions from -364 to -323 and from -122 to -63, which contain the consensus binding sequences for PU.1 (GGAA) and Sp1 (GGGCGG), respectively, are important for the transcriptional activity. Gel-shift and supershift assays revealed that PU.1 and Sp1 bind to the these regions through their consensus binding motifs. In addition, introduction of mutations into these motifs resulted in marked decrease in the promoter activity. These results indicate that PU.1 and Sp1 are essential for the transcriptional activity of the tec promoter and suggest that the cooperation of PU.1 and Sp1 plays a substantial role in the preferential expression of the Tec molecule in the hematopoietic lineages. (C) 1997 Academic Press.