AKAP-Anchored PKA Maintains Neuronal L-type Calcium Channel Activity and NFAT Transcriptional Signaling

•LTCC-NFAT transcriptional coupling in neurons requires AKAP anchoring of CaN and PKA•AKAP79/150-anchored PKA opposes CaN to regulate basal LTCC phosphorylation•AKAP79/150-anchored PKA maintains LTCC Ca2+ influx required for CaN-NFAT signaling•Basal PKA activity in AKAP complexes can gate other signaling outputs

SummaryL-type voltage-gated Ca2+ channels (LTCC) couple neuronal excitation to gene transcription. LTCC activity is elevated by the cyclic AMP (cAMP)-dependent protein kinase (PKA) and depressed by the Ca2+-dependent phosphatase calcineurin (CaN), and both enzymes are localized to the channel by A-kinase anchoring protein 79/150 (AKAP79/150). AKAP79/150 anchoring of CaN also promotes LTCC activation of transcription through dephosphorylation of the nuclear factor of activated T cells (NFAT). We report here that the basal activity of AKAP79/150-anchored PKA maintains neuronal LTCC coupling to CaN-NFAT signaling by preserving LTCC phosphorylation in opposition to anchored CaN. Genetic disruption of AKAP-PKA anchoring promoted redistribution of the kinase out of postsynaptic dendritic spines, profound decreases in LTCC phosphorylation and Ca2+ influx, and impaired NFAT movement to the nucleus and activation of transcription. Thus, LTCC-NFAT transcriptional signaling in neurons requires precise organization and balancing of PKA and CaN activities in the channel nanoenvironment, which is only made possible by AKAP79/150 scaffolding.

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