Down-regulation of IL-2 production in T lymphocytes by phosphorylated protein kinase A-RIIbeta.
The beta isoform of the type II regulatory subunit (RIIbeta) of protein kinase A suppresses CREB transcriptional activity and c-Fos production in T cells following activation via the TCR. Because CREB is an integral nuclear transcription factor for IL-2 production by T cells, we tested the hypothesis that RIIbeta down-regulates IL-2 expression and IL-2 production in T cells. Stable transfection of RIIbeta in Jurkat T cells led to an approximately 90% reduction in IL-2 mRNA and IL-2 protein following T cell activation. The inhibition of IL-2 production was associated with phosphorylation of the RIIbeta subunit at serine 114 (pRIIbeta) and localization of pRIIbeta in intranuclear clusters. A serine 114 phosphorylation-defective mutant, RIIbeta(S114A), did not form these intranuclear clusters as well as wild-type RIIbeta, and did not inhibit IL-2 mRNA and protein synthesis, indicating that serine 114 phosphorylation is required for both nuclear localization and down-regulation of IL-2 production by RIIbeta. In contrast to its effect on IL-2, RIIbeta induced constitutive up-regulation of CD154 mRNA and cell surface expression. Thus, pRIIbeta differentially regulates gene expression following T cell activation. Unexpectedly, we also found that stable overexpression of another protein kinase A regulatory subunit, RIalpha, had the opposite effect on IL-2 expression, causing a 3- to 4-fold increase in IL-2 production following stimulation. In summary, our data demonstrate a novel mechanism by which serine 114 phosphorylation and nuclear localization of RIIbeta controls the regulation of gene expression in T cells.
Elliott
Michael R
MR
Department of Microbiology and Immunology, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, NC 27157, USA.
Shanks
Ryan A
RA
Khan
Islam U
IU
Brooks
James W
JW
Burkett
Pamela J
PJ
Nelson
Brandy J
BJ
Kyttaris
Vasileios
V
Juang
Yuang-Taung
YT
Tsokos
George C
GC
Kammer
Gary M
GM
D021581:Active Transport, Cell Nucleus; D023201:CD40 Ligand / Q000096:biosynthesis; D054757:Cyclic AMP-Dependent Protein Kinase RIIbeta Subunit; D054756:Cyclic AMP-Dependent Protein Kinase RIalpha Subunit; D054746:Cyclic AMP-Dependent Protein Kinase Type II; D017868:Cyclic AMP-Dependent Protein Kinases / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D015536:Down-Regulation / Q000235:genetics / Q000276:immunology*; D006801:Humans; D007376:Interleukin-2 / Q000096:biosynthesis*; D019169:Jurkat Cells; D008213:Lymphocyte Activation; D010766:Phosphorylation; D012333:RNA, Messenger / Q000032:analysis; D012694:Serine; D013601:T-Lymphocytes / Q000378:metabolism*; D014162:Transfection; D015854:Up-Regulation / Q000276:immunology
D054757:Cyclic AMP-Dependent Protein Kinase RIIbeta Subunit; D054756:Cyclic AMP-Dependent Protein Kinase RIalpha Subunit; D007376:Interleukin-2; C517834:PRKAR1A protein, human; C517837:PRKAR2B protein, human; D012333:RNA, Messenger; D023201:CD40 Ligand; D012694:Serine; D054746:Cyclic AMP-Dependent Protein Kinase Type II; D017868:Cyclic AMP-Dependent Protein Kinases