title: Protein kinase A regulatory subunit type II beta directly interacts with and suppresses CREB transcriptional activity in activated T cells.
abstract: Levels of the type IIbeta regulatory subunit (RIIbeta) of protein kinase A are abnormally high in the nuclei of T cells of some subjects with the autoimmune disorder systemic lupus erythematosus (SLE). However, the role of nuclear RIIbeta in the regulation of T cell function is unknown. Based on previous studies demonstrating that nuclear protein kinase A-RII subunits can modify cAMP response element (CRE)-dependent transcription, we tested the hypothesis that nuclear RIIbeta can alter CRE-directed gene expression in T cells through interaction with the nuclear transcription factor CRE-binding protein CREB. To test this hypothesis, we used the RIIbeta-deficient S49 and the Jurkat T cell lines. In both cell lines, transient transfection of RIIbeta resulted in nuclear localization of a portion of the ectopically expressed RIIbeta. In vitro and in vivo analyses revealed a novel, specific interaction between RIIbeta and CREB that mapped to the N-terminal 135 aa of RIIbeta. In functional studies, RIIbeta inhibited the transcriptional activity of a GAL4-CREB fusion protein by 67% in Jurkat T cells following activation with anti-CD3 and anti-CD28 mAbs. Importantly, deletion of the CREB-binding region of RIIbeta completely abrogated inhibition. Additionally, RIIbeta suppressed CRE-directed reporter gene expression and substantially reduced induction of promoter activity and endogenous protein levels of the CREB-dependent gene, c-fos, in activated T cells. We conclude that nuclear RIIbeta can act as a repressor of CREB transcriptional activity in T cells, providing a potential functional significance for aberrant levels of nuclear RIIbeta in systemic lupus erythematosus T cells.
mesh_terms: D000818:Animals; D050882:CREB-Binding Protein; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000201:enzymology / Q000378:metabolism; D017362:Cyclic AMP Response Element-Binding Protein / Q000037:antagonists & inhibitors* / Q000235:genetics* / Q000378:metabolism; D054757:Cyclic AMP-Dependent Protein Kinase RIIbeta Subunit; D054746:Cyclic AMP-Dependent Protein Kinase Type II; D017868:Cyclic AMP-Dependent Protein Kinases / Q000096:biosynthesis / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D019169:Jurkat Cells; D008213:Lymphocyte Activation / Q000235:genetics*; D051379:Mice; D008807:Mice, Inbred BALB C; D009687:Nuclear Proteins / Q000378:metabolism; D010446:Peptide Fragments / Q000378:metabolism; D010449:Peptide Mapping; D010766:Phosphorylation; D011485:Protein Binding / Q000235:genetics / Q000276:immunology; D021122:Protein Subunits / Q000096:biosynthesis / Q000378:metabolism / Q000502:physiology; D012097:Repressor Proteins / Q000096:biosynthesis / Q000378:metabolism / Q000502:physiology*; D020218:Response Elements / Q000276:immunology; D012694:Serine / Q000378:metabolism; D016176:T-Lymphocyte Subsets / Q000201:enzymology* / Q000276:immunology / Q000378:metabolism; D015534:Trans-Activators / Q000037:antagonists & inhibitors* / Q000235:genetics* / Q000378:metabolism; D014162:Transfection
chemical_list: D017362:Cyclic AMP Response Element-Binding Protein; D054757:Cyclic AMP-Dependent Protein Kinase RIIbeta Subunit; D009687:Nuclear Proteins; C517837:PRKAR2B protein, human; D010446:Peptide Fragments; C517838:Prkar2b protein, mouse; D021122:Protein Subunits; D012097:Repressor Proteins; D015534:Trans-Activators; D012694:Serine; D050882:CREB-Binding Protein; C494363:CREBBP protein, human; C494364:Crebbp protein, mouse; D054746:Cyclic AMP-Dependent Protein Kinase Type II; D017868:Cyclic AMP-Dependent Protein Kinases