Role of plasma membrane-associated AKAPs for the regulation of cardiac IK1current by protein kinase A.
The cardiac IK1current stabilizes the resting membrane potential of cardiomyocytes. Protein kinase A (PKA) induces an inhibition of IK1current which strongly promotes focal arrhythmogenesis. The molecular mechanisms underlying this regulation have only partially been elucidated yet. Furthermore, the role of A-kinase anchoring proteins (AKAPs) in this regulation has not been examined to date. The objective of this project was to elucidate the molecular mechanisms underlying the inhibition of IK1by PKA and to identify novel molecular targets for antiarrhythmic therapy downstream β-adrenoreceptors. Patch clamp and voltage clamp experiments were used to record currents and co-immunoprecipitation, and co-localization experiments were performed to show spatial and functional coupling. Activation of PKA inhibited IK1current in rat cardiomyocytes. This regulation was markedly attenuated by disrupting PKA-binding to AKAPs with the peptide inhibitor AKAP-IS. We observed functional and spatial coupling of the plasma membrane-associated AKAP15 and AKAP79 to Kir2.1 and Kir2.2 channel subunits, but not to Kir2.3 channels. In contrast, AKAPyotiao had no functional effect on the PKA regulation of Kir channels. AKAP15 and AKAP79 co-immunoprecipitated with and co-localized to Kir2.1 and Kir2.2 channel subunits in ventricular cardiomyocytes. In this study, we provide evidence for coupling of cardiac Kir2.1 and Kir2.2 subunits with the plasma membrane-bound AKAPs 15 and 79. Cardiac membrane-associated AKAPs are a functionally essential part of the regulatory cascade determining IK1current function and may be novel molecular targets for antiarrhythmic therapy downstream from β-adrenoreceptors.
Department of Cardiology, Medical University Hospital Heidelberg, Im Neuenheimer Feld 410, D-69120, Heidelberg, Germany. claudia.seyler@med.uni-heidelberg.de.|DZHK (German Centre for Cardiovascular Research), partner site Heidelberg/Mannheim, Heidelberg, Germany. claudia.seyler@med.uni-heidelberg.de.
Claudia
C
Seyler
Department of Cardiology, Medical University Hospital Heidelberg, Im Neuenheimer Feld 410, D-69120, Heidelberg, Germany.
Daniel
D
Scherer
Department of Cardiology, Medical University Hospital Heidelberg, Im Neuenheimer Feld 410, D-69120, Heidelberg, Germany.
Christoph
C
Köpple
Department of Cardiology, Medical University Hospital Heidelberg, Im Neuenheimer Feld 410, D-69120, Heidelberg, Germany.
Martin
M
Kulzer
Department of Cardiac Surgery, Medical University Hospital Heidelberg, Heidelberg, Germany.
Sevil
S
Korkmaz
Department of Cardiology, Medical University Hospital Heidelberg, Im Neuenheimer Feld 410, D-69120, Heidelberg, Germany.
Panagiotis
P
Xynogalos
Department of Cardiology, Medical University Hospital Heidelberg, Im Neuenheimer Feld 410, D-69120, Heidelberg, Germany.|DZHK (German Centre for Cardiovascular Research), partner site Heidelberg/Mannheim, Heidelberg, Germany.
Dierk
D
Thomas
Department of Cardiology, Medical University Hospital Heidelberg, Im Neuenheimer Feld 410, D-69120, Heidelberg, Germany.|DZHK (German Centre for Cardiovascular Research), partner site Heidelberg/Mannheim, Heidelberg, Germany.
Ziya
Z
Kaya
Department of Cardiology, Medical University Hospital Heidelberg, Im Neuenheimer Feld 410, D-69120, Heidelberg, Germany.|DZHK (German Centre for Cardiovascular Research), partner site Heidelberg/Mannheim, Heidelberg, Germany.
Eberhard
E
Scholz
Department of Cardiology, Medical University Hospital Heidelberg, Im Neuenheimer Feld 410, D-69120, Heidelberg, Germany.|DZHK (German Centre for Cardiovascular Research), partner site Heidelberg/Mannheim, Heidelberg, Germany.
Johannes
J
Backs
Department of Cardiology, Medical University Hospital Heidelberg, Im Neuenheimer Feld 410, D-69120, Heidelberg, Germany.
Christoph
C
Karle
Department of Cardiology, Medical University Hospital Heidelberg, Im Neuenheimer Feld 410, D-69120, Heidelberg, Germany.|DZHK (German Centre for Cardiovascular Research), partner site Heidelberg/Mannheim, Heidelberg, Germany.
Hugo A
HA
Katus
Department of Cardiology, Medical University Hospital Heidelberg, Im Neuenheimer Feld 410, D-69120, Heidelberg, Germany.|DZHK (German Centre for Cardiovascular Research), partner site Heidelberg/Mannheim, Heidelberg, Germany.
Edgar
E
Zitron
D054758:A Kinase Anchor Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism; D000818:Animals; D016466:CHO Cells; D002462:Cell Membrane / Q000187:drug effects / Q000201:enzymology*; D003412:Cricetulus; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D004789:Enzyme Activation; D020536:Enzyme Activators / Q000494:pharmacology; D057809:HEK293 Cells; D006801:Humans; D047468:Immunoprecipitation; D015640:Ion Channel Gating; D008564:Membrane Potentials; D008845:Microinjections; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000201:enzymology*; D018408:Patch-Clamp Techniques; D010455:Peptides / Q000494:pharmacology; D024661:Potassium Channels, Inwardly Rectifying / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D051381:Rats; D014162:Transfection; D014981:Xenopus
D054758:A Kinase Anchor Proteins; D048868:Adaptor Proteins, Signal Transducing; C415703:Akap5 protein, rat; C526078:Akap7 protein, rat; D020536:Enzyme Activators; C575188:KCNJ2 protein, rat; C489463:Kir2.2 channel; D010455:Peptides; D024661:Potassium Channels, Inwardly Rectifying; D017868:Cyclic AMP-Dependent Protein Kinases
AKAPs; Adrenergic signaling; Arrhythmogenesis; Cardiac IK1 current; PKA