COMPARISON OF PROMOTERS FOR THE MURINE AND HUMAN P-SELECTIN GENES SUGGESTS SPECIES-SPECIFIC AND CONSERVED MECHANISMS FOR TRANSCRIPTIONAL REGULATION IN ENDOTHELIAL-CELLS

P-selectin, an adhesion receptor for leukocytes, is constitutively exp ressed in megakaryocytes and endothelial cells. Tumor necrosis factor- alpha (TNF-alpha) or lipopolysaccharide (LPS) increases synthesis of P -selectin in murine but not in human endothelial cells. To identify po tential species-specific and conserved mechanisms for regulation of ex pression of P-selectin, we cloned the 5'-flanking region of the murine P-selectin gene and compared its features with those previously repor ted for the human gene. The murine and human genes shared conserved St at-like, Hox, Ets, GATA, and GT-IIC elements. In the murine gene, a co nserved GATA element bound to GATA-2 and functioned as a positive regu latory element, whereas a conserved Ets element bound to GA-binding pr otein and functioned as a negative regulatory element. Significantly, the murine P-selectin gene had several features not found in the human gene. These included an insertion from -987 to -649 that contained ta ndem GATA and tandem AP1-like sequences, which resembled enhancers in beta-globin locus control regions. Both tandem elements bound specific ally to nuclear proteins. The murine gene lacked the unique kappa B si te specific for p50 or p52 homodimers found in the human gene. Instead , it contained two tandem kappa B elements and a variant activating tr anscription factor/cAMP response element site, which closely resembled sites in the E-selectin gene that are required for TNF-alpha-or LPS-i nducible expression. TNF-alpha or LPS augmented expression of a report er gene driven by the murine, but not the human, P-selectin promoter i n transfected endothelial cells. Deletional analysis of the murine 5'- flanking region revealed several sequences that were required for eith er constitutive or inducible expression. These data suggest that both species-specific and conserved mechanisms regulate transcription of th e human and murine P-selectin genes.