No abstract

The stimulatory effect of PGE 1 on the activity of the Na, K-ATPase in MDCK cells is associated with an increase in the rate of transcription of the Na, K-ATPase β1 subunit gene, and an increase in the rate of biosynthesis of the Na, K-ATPase [1]. In order to further define the molecular mechanisms, transient transfection and biosynthesis studies were conducted with Dibutyryl cAMP resistant (DB r ) MDCK cells, defective in cAMP dependent protein kinase, and PGE 1 Independent (PGE 1 Ind) MDCK cells with elevated intracellular cAMP. Transient transfection studies with the human Na, K-ATPase β1 promoter/luciferase construct, pHβ1-1141 Luc [2], showed that the stimulatory effect of PGE 1 and 8Br-cAMP on β1 subunit gene transcription is retained in the DB r and PGE 1 independent variants. However, the stimulatory effect of PGE 1 and 8Br-cAMP on Na, K-ATPase biosynthesis was lost in DB r (unlike PGE 1 Ind) variants. These results can be explained by a defect in posttranscriptional regulation.