Comparison of promoters for the murine and human P-selectin genes suggests species-specific and conserved mechanisms for transcriptional regulation in endothelial cells

Abstract

P-selectin, an adhesion receptor for leukocytes, is constitutively expressed in megakaryocytes and endothelial cells. Tumor necrosis factor-α (TNF-α) or lipopolysaccharide (LPS) increases synthesis of P-selectin in murine but not in human endothelial cells. To identify potential species- specific and conserved mechanisms for regulation of expression of P-selectin, we cloned the 5'-flanking region of the murine P-selectin gene and compared its features with those previously reported for the human gene. The murine and human genes shared conserved Stat-like, Hox, Ets, GATA, and GT-IIC elements. In the murine gene, a conserved GATA element bound to GATA-2 and functioned as a positive regulatory element, whereas a conserved Ets element bound to GA-binding protein 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 tandem GATA and tandem AP1-like sequences, which resembled enhancers in β- globin locus control regions. Both tandem elements bound specifically to nuclear proteins. The murine gene lacked the unique κB site specific for p50 or p52 homodimers found in the human gene. Instead, it contained two tandem κB elements and a variant activating transcription factor/cAMP response element site, which closely resembled sites in the E-selectin gene that are required for TNF-α-or LPS-inducible expression. TNF-α or LPS augmented expression of a reporter gene driven by the murine, but not the human, P- selectin promoter in transfected endothelial cells. Deletional analysis of the murine 5'-flanking region revealed several sequences that were required for either constitutive or inducible expression. These data suggest that both species-specific and conserved mechanisms regulate transcription of the human and murine P-selectin genes.