Dopaminergic Modulation of Voltage-Gated Na⁺Current in Rat Hippocampal Neurons Requires Anchoring of cAMP-Dependent Protein Kinase

Abstract

Activation of D1-like dopamine (DA) receptors reduces peak Na(+) current in acutely isolated hippocampal neurons via a modulatory mechanism involving phosphorylation of the Na(+) channel alpha subunit by cAMP-dependent protein kinase (PKA). Peak Na(+) current is reduced 20-50% in the presence of the D1 agonist SKF 81297 or the PKA activator Sp-5,6-dichloro-l-beta-d-ribofuranosyl benzimidazole-3',5'-cyclic monophosphorothionate (cBIMPS). Co-immunoprecipitation experiments show that Na(+) channels are associated with PKA and A-kinase-anchoring protein 15 (AKAP-15), and immunocytochemical labeling reveals their co-localization in the cell bodies and proximal dendrites of hippocampal pyramidal neurons. Anchoring of PKA near the channel by an AKAP, which binds the RII alpha regulatory subunit, is necessary for Na(+) channel modulation in acutely dissociated hippocampal pyramidal neurons. Intracellular dialysis with the anchoring inhibitor peptides Ht31 from a human thyroid AKAP and AP2 from AKAP-15 eliminated the modulation of the Na(+) channel by the D1-agonist SKF 81297 and the PKA activator cBIMPS. In contrast, dialysis with the inactive proline-substituted control peptides Ht31-P and AP2-P had little effect on the D1 and PKA modulation. Therefore, we conclude that modulation of the Na(+) channel by activation of D1-like DA receptors requires targeted localization of PKA near the channel to achieve phosphorylation of the alpha subunit and to modify the functional properties of the channel.

The Role of the Theta Isoform of Protein Kinase C (PKC) in Activity-Dependent Synapse Elimination: Evidence from the PKC Theta Knock-Out MouseIn VivoandIn Vitro

“…(2) Activation of peptidergic (e.g., CGRP) receptors locally activates PKA. As noted in previous publications (Li et al, 2002;Nelson et al, 2003), this localization of PKA would be attributable to interactions of the kinase with anchoring proteins (AKAPs) (Cantrell et al, 1999;Sik et al, 2000). (3) PKA phosphorylates the AChR (or other critical scaffold protein) so that the receptor is stabilized in the synaptic membrane.…”

β-Adrenergic regulation requires direct anchoring of PKA to cardiac Ca V 1.2 channels via a leucine zipper interaction with A kinase-anchoring protein 15

“…In addition, AKAP79͞150 is also expressed in the brain and has been implicated in PKA-independent trafficking of Ca V 1.2 channels (51). Because AKAP15 and Ca V 1.2 channels are both present in the dendrites and cell bodies of brain neurons (52,53), it is possible that AKAP15 may be involved in PKA regulation of Ca V 1.2 channels in neurons as well. Moreover, because Ca V 1.3 and Ca V 1.4 channels also contain the conserved AKAP15-binding domain, regulation of these channels in neurons, endocrine cells, cardiac pacemaker cells, retinal rods and cones, and auditory hair cells may also involve the direct targeting of PKA by AKAP15.…”

“…Monoclonal anti-Myc antibody was purchased from Invitrogen. AKAP15 LZ (38-54) (acetyl-ENAVLKAVQQYLEETQN-amide) and AKAP15 LZM (38)(39)(40)(41)(42)(43)(44)(45)(46)(47)(48)(49)(50)(51)(52)(53)(54) peptides (acetyl-ENAVAKAVQQYAEETQN-amide) were synthesized and purified by Genemed Biotechnologies (South San Francisco, CA). PKI(5-24)-amide was obtained from Peninsula Laboratories, and HT31 peptide was synthesized and purified as described (38).…”

“…Data acquisition and command potentials were controlled by PCLAMP software (v8.0, Axon Instruments), and data were stored for later off-line analysis. HT31, AKAP15 LZ (38)(39)(40)(41)(42)(43)(44)(45)(46)(47)(48)(49)(50)(51)(52)(53)(54), and AKAP15 LZM (38-54) peptides were prepared and used as described (44). The effect of isoproterenol (1 M) on I Ca in the absence and presence of peptides was examined 10-15 min after establishing the whole-cell configuration.…”

Identification of a Novel A-kinase Anchoring Protein 18 Isoform and Evidence for Its Role in the Vasopressin-induced Aquaporin-2 Shuttle in Renal Principal Cells

“…AKAP18␣ may also potentiate insulin secretion from pancreatic ␤-cells (8). In addition, AKAP18␣ interacts with brain Na ϩ channels, thereby enabling channel phosphorylation and downregulation by PKA (15,16). AKAP18␤ consists of 104 amino acid residues.…”