Cutting Edge: A-Kinase Anchor Proteins Are Involved in Maintaining Resting T Cells in an Inactive State

A-kinase anchor proteins (AKAPs) target protein kinase A (PKA) to different subcellular locations and are thought to play important roles in the cAMP signaling pathway. The aims of this study were to determine whether T cells express AKAPs and, if so, to establish their physiological significance. CD4(+) T cells were found to express eight AKAPs. Disruption of the AKAP-PKA interaction caused high levels of IL-2, IL-4, IL-5, and IFN-gamma production in the absence of stimulation via CD3epsilon and CD28 molecules. Disruption of the AKAP-PKA interaction acted synergistically with suboptimal doses of Ag in boosting proliferative responses of T cells. Finally, disruption of the AKAP-PKA interaction rendered T cells insensitive to cAMP-elevating agents. It was concluded that AKAPs, through their association with PKA, are involved in maintaining T cell homeostasis and in regulating the sensitivity of T cells to incoming cAMP signals.