Eosinophil-specific regulation of gp91(phox) gene expression by transcription factors GATA-1 and GATA-2

The glycoprotein gp91(phox) is an essential component of the phagocyte NADP H oxidase and is expressed in eosinophils, neutrophils, monocytes, and B-ly mphocytes, We previously suggested an eosinophil-specific mechanism of gp91 (phox) gene expression. To elucidate the mechanism, we performed functional assays on deletion mutants of the gp91(phox) promoter in various types of gp91(phox)-expressing cells. A 10-base pair (bp) region from bp -105 to -96 of the promoter activated transcription of the gene in eosinophilic cells, but not in neutrophilic, monocytic, or B-lymphocytic cells, A 2-bp mutatio n introduced into the GATA site spanning bp -101 to -96 (-98GATA site) of t he fragment abolished its activity. Gel shift assays using a GATA competito r and specific antibodies demonstrated that both GATA-1 and GATA-2 specific ally bound to the -98GATA site with similar affinities. Individual transfec tion of GATA-1 and GATA-2 into Jurkat cells, which have neither endogenous GATA-1 nor GATA-2, activated the -105/+12 construct in a -98GATA site-depen dent manner. Combined transfection of GATA-1 and GATA-2 activated the promo ter less than transfection of GATA-1 alone. These results suggest that GATA -1 is an activator and that GATA-2 is a relative competitive inhibitor of G ATA-1 in the expression of the gp91(phox) gene in human eosinophils.