Elevation of cyclic AMP in Jurkat T-cells provokes distinct transcriptional responses through the protein kinase A (PKA) and exchange protein activated by cyclic AMP (EPAC) pathways.
Elevating cyclic AMP with a combination of forskolin and IBMX (Fskn/IBMX) was found as the cause of G1 growth arrest in Jurkat T-cells, concomitant with an induction of the cyclin-dependent kinase inhibitor, p27Kip1. The protein kinase inhibitor H-89, which can discriminate between EPAC and PKA pathways, blocked the inhibition in cell growth and induction of p27Kip1, indicating an involvement of PKA, but not EPAC. The EPAC-specific cyclic AMP analogue, 8-CPT-2Me-cAMP was able to activate Rap1, but failed to induce growth arrest or induction p27Kip1. These results demonstrate that PKA, and not EPAC, mediates cyclic AMP-dependent growth arrest in Jurkat T-cells. To further investigate a role for EPAC in these cells, we carried out cDNA microarray analysis of cells stimulated with 8-CPT-2Me-cAMP. We identified separate groups of genes whose expression was either induced or repressed in response to 8-CPT-2Me-cAMP. This provides the first demonstration that EPAC can regulate gene expression, although it may not be involved in cell cycle control. Finally, we identify c-Jun as a transcription factor whose activity is specifically down-regulated following EPAC activation, but not PKA. The control of gene expression by cyclic AMP in Jurkat T-cells therefore requires input from the EPAC signalling cascade.
Fuld
Suzanne
S
Molecular Pharmacology Group, Division of Biochemistry and Molecular Biology, Faculty of Biomedical and Life Sciences, University of Glasgow, Davidson Building, Glasgow G12 8QQ, Scotland, UK.
Borland
Gillian
G
Yarwood
Stephen J
SJ
D002453:Cell Cycle / Q000502:physiology*; D000242:Cyclic AMP / Q000031:analogs & derivatives / Q000235:genetics / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016193:G1 Phase / Q000502:physiology; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism*; D006801:Humans; D019169:Jurkat Cells; D015398:Signal Transduction; D015533:Transcriptional Activation; D015854:Up-Regulation; D020827:rap1 GTP-Binding Proteins / Q000378:metabolism
D004791:Enzyme Inhibitors; D020662:Guanine Nucleotide Exchange Factors; C116122:RAPGEF3 protein, human; D050760:Cyclin-Dependent Kinase Inhibitor p27; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D020827:rap1 GTP-Binding Proteins