Protein Kinase A Regulatory Subunit Type IIβ Directly Interacts with and Suppresses CREB Transcriptional Activity in Activated T Cells

• Published in: The Journal of immunology (1950) Vol. 171; no. 7; pp. 3636 - 3644
• Main Authors: Elliott, Michael R., Tolnay, Mate, Tsokos, George C., Kammer, Gary M.
• Format: Journal Article
• Language: English
• Published: United States 01.10.2003
• Subjects: Animals; Cell Line, Tumor; Cell Nucleus - enzymology; Cell Nucleus - metabolism; CREB-Binding Protein; Cyclic AMP Response Element-Binding Protein - antagonists & inhibitors; Cyclic AMP Response Element-Binding Protein - genetics; Cyclic AMP Response Element-Binding Protein - metabolism; Cyclic AMP-Dependent Protein Kinase RIIbeta Subunit; Cyclic AMP-Dependent Protein Kinase Type II; Cyclic AMP-Dependent Protein Kinases - biosynthesis; Cyclic AMP-Dependent Protein Kinases - metabolism; Cyclic AMP-Dependent Protein Kinases - physiology; Humans; Jurkat Cells; Lymphocyte Activation - genetics; Mice; Mice, Inbred BALB C; Nuclear Proteins - metabolism; Peptide Fragments - metabolism; Peptide Mapping; Phosphorylation; Protein Binding - genetics; Protein Binding - immunology; Protein Subunits - biosynthesis; Protein Subunits - metabolism; Protein Subunits - physiology; Repressor Proteins - biosynthesis; Repressor Proteins - metabolism; Repressor Proteins - physiology; Response Elements - immunology; Serine - metabolism; T-Lymphocyte Subsets - enzymology; T-Lymphocyte Subsets - immunology; T-Lymphocyte Subsets - metabolism; Trans-Activators - antagonists & inhibitors; Trans-Activators - genetics; Trans-Activators - metabolism; Transfection
• ISSN: 0022-1767; 1550-6606
• DOI: 10.4049/jimmunol.171.7.3636

Levels of the type IIβ regulatory subunit (RIIβ) 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 RIIβ 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 RIIβ 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 RIIβ-deficient S49 and the Jurkat T cell lines. In both cell lines, transient transfection of RIIβ resulted in nuclear localization of a portion of the ectopically expressed RIIβ. In vitro and in vivo analyses revealed a novel, specific interaction between RIIβ and CREB that mapped to the N-terminal 135 aa of RIIβ. In functional studies, RIIβ 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 RIIβ completely abrogated inhibition. Additionally, RIIβ 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 RIIβ can act as a repressor of CREB transcriptional activity in T cells, providing a potential functional significance for aberrant levels of nuclear RIIβ in systemic lupus erythematosus T cells.