The inotropic peptide βARKct improves βAR responsiveness in normal and failing cardiomyocytes through Gβγ-mediated L-type calcium current disinhibition

• Verfasst von: Völkers, Mirko [VerfasserIn]
• Verfasst von: Weidenhammer, Christian [VerfasserIn]
• Verfasst von: Herzog, Nicole [VerfasserIn]
• Verfasst von: Qiu, Gang [VerfasserIn]
• Verfasst von: Spaich, Kristin [VerfasserIn]
• Verfasst von: von Wegner, Frederic [VerfasserIn]
• Verfasst von: Peppel, Karsten [VerfasserIn]
• Verfasst von: Müller, Oliver J. [VerfasserIn]
• Verfasst von: Schinkel, Stefanie [VerfasserIn]
• Verfasst von: Rabinowitz, Joseph E. [VerfasserIn]
• Verfasst von: Hippe, Hans-Jörg [VerfasserIn]
• Verfasst von: Brinks, Henriette [VerfasserIn]
• Verfasst von: Katus, Hugo [VerfasserIn]
• Verfasst von: Koch, Walter J. [VerfasserIn]
• Verfasst von: Eckhart, Andrea D. [VerfasserIn]
• Verfasst von: Friedrich, Oliver [VerfasserIn]
• Verfasst von: Most, Patrick [VerfasserIn]
• Titel: The inotropic peptide βARKct improves βAR responsiveness in normal and failing cardiomyocytes through Gβγ-mediated L-type calcium current disinhibition
• Verf.angabe: Mirko Völkers, Christian Weidenhammer, Nicole Herzog, Gang Qiu, Kristin Spaich, Frederic von Wegner, Karsten Peppel, Oliver J. Müller, Stefanie Schinkel, Joseph E. Rabinowitz, Hans-Jörg Hippe, Henriette Brinks, Hugo A. Katus, Walter J. Koch, Andrea D. Eckhart, Oliver Friedrich, Patrick Most
• Jahr: 2011
• Umfang: 13 S.
• Fussnoten: Ursprünglich veröffentlicht Version 1: 24 Nov 2010 ; Im Text ist "βγ" tiefgestellt ; Gesehen am 25.10.2022
• Titel Quelle: Enthalten in: Circulation research
• Ort Quelle: New York, NY : Assoc., 1953
• Jahr Quelle: 2011
• Band/Heft Quelle: 108(2011), 1 vom: 7. Jan., Seite 27-39
• ISSN Quelle: 1524-4571
• DOI: doi:10.1161/CIRCRESAHA.110.225201
• Datenträger: Online-Ressource
• Sprache: eng
• Sach-SW: G proteins
• Sach-SW: L-type Ca2+ channel
• Sach-SW: β-adrenergic receptor
• Sach-SW: βARKct
• K10plus-PPN: 1819880524

Abstract

Rationale: - - The Gβγ-sequestering peptide β-adrenergic receptor kinase (βARK)ct derived from the G-protein-coupled receptor kinase (GRK)2 carboxyl terminus has emerged as a promising target for gene-based heart failure therapy. Enhanced downstream cAMP signaling has been proposed as the underlying mechanism for increased β-adrenergic receptor (βAR) responsiveness. However, molecular targets mediating improved cardiac contractile performance by βARKct and its impact on Gβγ-mediated signaling have yet to be fully elucidated. - - Objective: - - We sought to identify Gβγ-regulated targets and signaling mechanisms conveying βARKct-mediated enhanced βAR responsiveness in normal (NC) and failing (FC) adult rat ventricular cardiomyocytes. - - Methods and Results: - - Assessing viral-based βARKct gene delivery with electrophysiological techniques, analysis of contractile performance, subcellular Ca2+ handling, and site-specific protein phosphorylation, we demonstrate that βARKct enhances the cardiac L-type Ca2+ channel (LCC) current (ICa) both in NCs and FCs on βAR stimulation. Mechanistically, βARKct augments ICa by preventing enhanced inhibitory interaction between the α1-LCC subunit (Cav1.2α) and liberated Gβγ subunits downstream of activated βARs. Despite improved βAR contractile responsiveness, βARKct neither increased nor restored cAMP-dependent protein kinase (PKA) and calmodulin-dependent kinase II signaling including unchanged protein kinase (PK)Cε, extracellular signal-regulated kinase (ERK)1/2, Akt, ERK5, and p38 activation both in NCs and FCs. Accordingly, although βARKct significantly increases ICa and Ca2+ transients, being susceptible to suppression by recombinant Gβγ protein and use-dependent LCC blocker, βARKct-expressing cardiomyocytes exhibit equal basal and βAR-stimulated sarcoplasmic reticulum Ca2+ load, spontaneous diastolic Ca2+ leakage, and survival rates and were less susceptible to field-stimulated Ca2+ waves compared with controls. - - Conclusion: - - Our study identifies a Gβγ-dependent signaling pathway attenuating cardiomyocyte ICa on βAR as molecular target for the Gβγ-sequestering peptide βARKct. Targeted interruption of this inhibitory signaling pathway by βARKct confers improved βAR contractile responsiveness through increased ICa without enhancing regular or restoring abnormal cAMP-signaling. βARKct-mediated improvement of ICa rendered cardiomyocytes neither susceptible to βAR-induced damage nor arrhythmogenic sarcoplasmic reticulum Ca2+ leakage.