Prostaglandins regulate transcription by means of prostaglandin response elements located in the promoters of mammalian Na,K-ATPase β1 subunit genes

Prostaglandins are potent products of arachidonic acid metabolism that play significant roles in regulating ion transport in the kidney. In the Madin Darby canine kidney (MDCK) cell line prostaglandin E₁ (PGE₁) stimulates the activity of the Na,K-ATPase and regulates transcription. Transient transfection studies conducted in MDCK cells with a human Na,K-ATPase β1 subunit promoter/luciferase construct, pHβ1-1141 Luc, showed a PGE₁ stimulation. The PGE₁ stimulation was inhibited by the PGE receptor antagonists SC19220 and AH6809, indicating the involvement of EP1 receptors (coupled to phospholipase C) and EP2 receptors (coupled to adenylate cyclase), respectively. A prostaglandin-regulatory element (PGRE) within the β1 subunit promoter (?110 to ?92, AGTCCCTGC) is sufficient to elicit a PGE₁ stimulation in a heterologous promoter (in pLUC-MCS). Studies with promoter mutants indicated that in addition to the PGRE, an adjacent Sp1 site was also essential for regulation by PGE₁. Consistent with the involvement of Sp1 are the results of DNA affinity precipitation studies, which indicate that Sp1 as well as CREB, and Sp3 all bind to the PGRE. The involvement of this PGRE in transcriptional regulation of the Na,K-ATPase β1 gene was examined in a number of species. Only human and chimpanzee promoters possessed an identical PGRE site, unlike dog, rat, and mouse, which possessed Sp1 sites in similar locations. Two alternative PGREs were subsequently identified. The sequence of the one of these PGREs (TGACCTTC, ?445 to ?438) was conserved throughout all species examined, suggesting its physiologic significance.