Phosphodiesterase 8 governs cAMP/PKA-dependent reduction of L-type calcium current in human atrial fibrillation: a novel arrhythmogenic mechanism.

Nefeli Grammatika Pavlidou, Shokoufeh Dobrev, Kira Beneke, Franziska Reinhardt, Simon Pecha, Eric Jacquet, Issam H Abu-Taha, Constanze Schmidt, Niels Voigt, Markus Kamler, Renate B Schnabel, Istvan Baczkó, Anne Garnier, Hermann Reichenspurner, Viacheslav O Nikolaev, Dobromir Dobrev, Cristina E Molina

Journal: European heart journal 2023;44(27):2483-2494

PMID: 36810794

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Abstract

AIMS

Atrial fibrillation (AF) is associated with altered cAMP/PKA signaling and an AF-promoting reduction of L-type Ca2+-current (ICa,L), the mechanisms of which are poorly understood. Cyclic-nucleotide phosphodiesterases (PDEs) degrade cAMP and regulate PKA-dependent phosphorylation of key calcium-handling proteins, including the ICa,L-carrying Cav1.2α1C subunit. The aim was to assess whether altered function of PDE type-8 (PDE8) isoforms contributes to the reduction of ICa,L in persistent (chronic) AF (cAF) patients.

METHODS AND RESULTS

mRNA, protein levels, and localization of PDE8A and PDE8B isoforms were measured by RT-qPCR, western blot, co-immunoprecipitation and immunofluorescence. PDE8 function was assessed by FRET, patch-clamp and sharp-electrode recordings. PDE8A gene and protein levels were higher in paroxysmal AF (pAF) vs. sinus rhythm (SR) patients, whereas PDE8B was upregulated in cAF only. Cytosolic abundance of PDE8A was higher in atrial pAF myocytes, whereas PDE8B tended to be more abundant at the plasmalemma in cAF myocytes. In co-immunoprecipitation, only PDE8B2 showed binding to Cav1.2α1C subunit which was strongly increased in cAF. Accordingly, Cav1.2α1C showed a lower phosphorylation at Ser1928 in association with decreased ICa,L in cAF. Selective PDE8 inhibition increased Ser1928 phosphorylation of Cav1.2α1C, enhanced cAMP at the subsarcolemma and rescued the lower ICa,L in cAF, which was accompanied by a prolongation of action potential duration at 50% of repolarization.

CONCLUSION

Both PDE8A and PDE8B are expressed in human heart. Upregulation of PDE8B isoforms in cAF reduces ICa,L via direct interaction of PDE8B2 with the Cav1.2α1C subunit. Thus, upregulated PDE8B2 might serve as a novel molecular mechanism of the proarrhythmic reduction of ICa,L in cAF.

Address: Institute of Experimental Cardiovascular Research and University Center of Cardiovascular Sciences, University Medical Center Hamburg Eppendorf (UKE), Martinistrasse 52, W23, 20246 Hamburg, Germany.; German Centre for Cardiovascular Research (DZHK), partner site Hamburg/Kiel/Lübeck, Potsdamer Strasse 58, 10785 Berlin, Germany.; Institute of Pharmacology, West German Heart and Vascular Center, University Duisburg-Essen, Hufelandstrasse 55, 45147 Essen, Germany.; Institute of Experimental Cardiovascular Research and University Center of Cardiovascular Sciences, University Medical Center Hamburg Eppendorf (UKE), Martinistrasse 52, W23, 20246 Hamburg, Germany.; German Centre for Cardiovascular Research (DZHK), partner site Hamburg/Kiel/Lübeck, Potsdamer Strasse 58, 10785 Berlin, Germany.; Department of Cardiovascular Surgery, University Heart Center Hamburg, Martinistrasse 52, O70, 20246 Hamburg, Germany.; German Centre for Cardiovascular Research (DZHK), partner site Hamburg/Kiel/Lübeck, Potsdamer Strasse 58, 10785 Berlin, Germany.; Department of Cardiovascular Surgery, University Heart Center Hamburg, Martinistrasse 52, O70, 20246 Hamburg, Germany.; Université Paris-Saclay, CNRS, Institut de Chimie des Substances Naturelles, UPR 2301, 1 avenue de la Terrasse, 91198 Gif-sur-Yvette, France.; Department of Cardiology, University Medical Center Heidelberg, Im Neuenheimer Feld 672, 69120 Heidelberg, Germany.; Institute of Pharmacology and Toxicology, University Medical Center Göttingen, Robert-Koch-Strasse 40, 37075 Göttingen, Germany.; German Centre for Cardiovascular Research (DZHK), partner Site Göttingen, Potsdamer Strasse 58, 10785 Berlin, Germany.; Cluster of Excellence 'Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells' (MBExC), University of Göttingen, Robert-Koch- Strasse 40, 37075 Göttingen, Germany.; Department of Thoracic and Cardiovascular Surgery, West German Heart and Vascular Center, University Duisburg-Essen, Hufelandstrasse 55, 45147 Essen, Germany.; German Centre for Cardiovascular Research (DZHK), partner site Hamburg/Kiel/Lübeck, Potsdamer Strasse 58, 10785 Berlin, Germany.; Cardiology Department, University Heart and Vascular Centre Hamburg-Eppendorf, Martinistrasse 52, O70, 20246 Hamburg, Germany.; Department Pharmacology and Pharmacotherapy, University of Szeged, H-6721, Szeged, Dóm tér 12, Szeged, Hungary.; Inserm, UMR-S 1180, Université Paris-Saclay, Faculté de pharmacie, 17 avenue des Sciences, 91400 Orsay, France.; Institute of Pharmacology, West German Heart and Vascular Center, University Duisburg-Essen, Hufelandstrasse 55, 45147 Essen, Germany.; Department of Medicine and Research Center, Montreal Heart Institute and Université de Montréal, 4100 Molson Street, Suite 340, H1Y 3N1 Montréal, Canada.; Department of Molecular Physiology & Biophysics, Baylor College of Medicine, One Baylor Plaza, 77030 Houston, USA.; Institute of Experimental Cardiovascular Research and University Center of Cardiovascular Sciences, University Medical Center Hamburg Eppendorf (UKE), Martinistrasse 52, W23, 20246 Hamburg, Germany.; German Centre for Cardiovascular Research (DZHK), partner site Hamburg/Kiel/Lübeck, Potsdamer Strasse 58, 10785 Berlin, Germany.; Institute of Pharmacology, West German Heart and Vascular Center, University Duisburg-Essen, Hufelandstrasse 55, 45147 Essen, Germany.

DOI: 10.1093/eurheartj/ehad086