Disruption of PKA anchoring to CaV1.2 channels via AKAP15 using competing peptides markedly inhibited the isoproterenol-induced increase in L-type Ca2+ currents in rat ventricular myocytes.
Direct anchoring of PKA to cardiac CaV1.2 channels by AKAP15 via a leucine zipper motif is required for beta-adrenergic regulation of L-type calcium currents.
Absolute Event Rate: 1.21% vs 1.68%
Activation of beta-adrenergic receptors and consequent phosphorylation by cAMP-dependent protein kinase A (PKA) greatly increases the L-type Ca2+ current through CaV1.2 channels in isolated cardiac myocytes. A kinase-anchoring protein 15 (AKAP15) coimmunoprecipitates with CaV1.2 channels isolated from rat heart membrane extracts and transfected cells, and it colocalizes with CaV1.2 channels and PKA in the transverse tubules of isolated ventricular myocytes. Site-directed mutagenesis studies reveal that AKAP15 directly interacts with the distal C terminus of the cardiac CaV1.2 channel via a leucine zipper-like motif. Disruption of PKA anchoring to CaV1.2 channels via AKAP15 using competing peptides markedly inhibits the beta-adrenergic regulation of CaV1.2 channels via the PKA pathway in ventricular myocytes. These results identify a conserved leucine zipper motif in the C terminus of the CaV1 family of Ca2+ channels that directly anchors an AKAP15-PKA signaling complex to ensure rapid and efficient regulation of L-type Ca2+ currents in response to beta-adrenergic stimulation and local increases in cAMP.
Hulme et al. (Mon,) conducted a other in Basic cardiac electrophysiology. Competing peptides (HT31, AKAP15 LZ) disrupting PKA-AKAP15 anchoring vs. No peptide or mutant peptide (AKAP15 LZm) was evaluated on Isoproterenol-induced increase in L-type Ca2+ current (ICa). Disruption of PKA anchoring to CaV1.2 channels via AKAP15 using competing peptides markedly inhibited the isoproterenol-induced increase in L-type Ca2+ currents in rat ventricular myocytes.