Functional properties of the rat phosphatase 1 alpha promoter

The aim of this study was to investigate the functional properties of the p romoter of the protein phosphatase 1 alpha catalytic subunit. Luciferase pl asmids with different fragments of the rat catalytic subunit of the protein phosphatase 1 alpha promoter ranging from -3.7 kbp to -59 bp were transien tly transfected into cells by the calcium-phosphate precipitation method. T he promoter activity was determined in the absence and presence of inotropi c agents which influencing the cAMP-depending pathway. The basal transcript ional activity decreased at fragment -124 bp and shorter fragments. To iden tify regions of regulatory importance we investigated the cAMP-dependent in fluence on the transcriptional activity. Stimulation of the complete promot er region with forskolin (1-100 muM) for 6 h led to a concentration-depende nt decrease of transcriptional activity. Moreover, regions shorter than 3.7 kbp were inhibited by forskolin (10 muM). Short time stimulation (10 min) with forskolin (10 muM) increased the transcriptional activity of only the 3.7 kbp fragment. The effects were antagonized by Rp-cAMPS, a specific anta gonist of protein kinase A, indicating cAMP-dependent effects. The results provide evidence for cAMP-dependent regulation of the protein phosphatase 1 alpha promotor.