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Keller K, Maass M, Dizayee S, Leiss V, Annala S, Köth J, Seemann WK, Müller-Ehmsen J, Mohr K, Nürnberg B, Engelhardt S, Herzig S, Birnbaumer L, Matthes J. Lack of Gαi2 leads to dilative cardiomyopathy and increased mortality in β1-adrenoceptor overexpressing mice. Cardiovasc Res 2015; 108:348-56. [PMID: 26464333 DOI: 10.1093/cvr/cvv235] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Accepted: 09/28/2015] [Indexed: 01/05/2023] Open
Abstract
AIMS Inhibitory G (Gi) proteins have been proposed to be cardioprotective. We investigated effects of Gαi2 knockout on cardiac function and survival in a murine heart failure model of cardiac β1-adrenoceptor overexpression. METHODS AND RESULTS β1-transgenic mice lacking Gαi2 (β1-tg/Gαi2 (-/-)) were compared with wild-type mice and littermates either overexpressing cardiac β1-adrenoceptors (β1-tg) or lacking Gαi2 (Gαi2 (-/-)). At 300 days, mortality of mice only lacking Gαi2 was already higher compared with wild-type or β1-tg, but similar to β1-tg/Gαi2 (-/-), mice. Beyond 300 days, mortality of β1-tg/Gαi2 (-/-) mice was enhanced compared with all other genotypes (mean survival time: 363 ± 21 days). At 300 days of age, echocardiography revealed similar cardiac function of wild-type, β1-tg, and Gαi2 (-/-) mice, but significant impairment for β1-tg/Gαi2 (-/-) mice (e.g. ejection fraction 14 ± 2 vs. 40 ± 4% in wild-type mice). Significantly increased ventricle-to-body weight ratio (0.71 ± 0.06 vs. 0.48 ± 0.02% in wild-type mice), left ventricular size (length 0.82 ± 0.04 vs. 0.66 ± 0.03 cm in wild types), and atrial natriuretic peptide and brain natriuretic peptide expression (mRNA: 2819 and 495% of wild-type mice, respectively) indicated hypertrophy. Gαi3 was significantly up-regulated in Gαi2 knockout mice (protein compared with wild type: 340 ± 90% in Gαi2 (-/-) and 394 ± 80% in β1-tg/Gαi2 (-/-), respectively). CONCLUSIONS Gαi2 deficiency combined with cardiac β1-adrenoceptor overexpression strongly impaired survival and cardiac function. At 300 days of age, β1-adrenoceptor overexpression alone had not induced cardiac hypertrophy or dysfunction while there was overt cardiomyopathy in mice additionally lacking Gαi2. We propose an enhanced effect of increased β1-adrenergic drive by the lack of protection via Gαi2. Gαi3 up-regulation was not sufficient to compensate for Gαi2 deficiency, suggesting an isoform-specific or a concentration-dependent mechanism.
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Affiliation(s)
- Kirsten Keller
- Department of Pharmacology, University of Cologne, Gleueler Strasse 24, 50931 Cologne, Germany
| | - Martina Maass
- Department of Internal Medicine III, University Hospital of Cologne, Cologne, Germany
| | - Sara Dizayee
- Department of Pharmacology, University of Cologne, Gleueler Strasse 24, 50931 Cologne, Germany
| | - Veronika Leiss
- Department of Pharmacology and Experimental Therapy, Institute of Experimental and Clinical Pharmacology and Toxicology, Eberhard Karls University Hospitals and Clinics, and Interfaculty Center of Pharmacogenomics and Drug Research, Tuebingen, Germany
| | - Suvi Annala
- Department of Pharmacology, University of Cologne, Gleueler Strasse 24, 50931 Cologne, Germany
| | - Jessica Köth
- Department of Pharmacology, University of Cologne, Gleueler Strasse 24, 50931 Cologne, Germany
| | - Wiebke K Seemann
- Department of Pharmacology, University of Cologne, Gleueler Strasse 24, 50931 Cologne, Germany
| | | | - Klaus Mohr
- Pharmacology and Toxicology Section, Institute of Pharmacy, University of Bonn, Bonn, Germany
| | - Bernd Nürnberg
- Department of Pharmacology and Experimental Therapy, Institute of Experimental and Clinical Pharmacology and Toxicology, Eberhard Karls University Hospitals and Clinics, and Interfaculty Center of Pharmacogenomics and Drug Research, Tuebingen, Germany
| | - Stefan Engelhardt
- Institute of Pharmacology and Toxicology, Technische Universität München, Munich, Germany
| | - Stefan Herzig
- Department of Pharmacology, University of Cologne, Gleueler Strasse 24, 50931 Cologne, Germany
| | - Lutz Birnbaumer
- Laboratory of Neurobiology, NIEHS, NIH (Department of Health and Human Services), Durham, USA
| | - Jan Matthes
- Department of Pharmacology, University of Cologne, Gleueler Strasse 24, 50931 Cologne, Germany
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Raake PW, Zhang X, Vinge LE, Brinks H, Gao E, Jaleel N, Li Y, Tang M, Most P, Dorn GW, Houser SR, Katus HA, Chen X, Koch WJ. Cardiac G-protein-coupled receptor kinase 2 ablation induces a novel Ca2+ handling phenotype resistant to adverse alterations and remodeling after myocardial infarction. Circulation 2012; 125:2108-18. [PMID: 22496128 DOI: 10.1161/circulationaha.111.044255] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
BACKGROUND G-protein-coupled receptor kinase 2 (GRK2) is a primary regulator of β-adrenergic signaling in the heart. G-protein-coupled receptor kinase 2 ablation impedes heart failure development, but elucidation of the cellular mechanisms has not been achieved, and such elucidation is the aim of this study. METHODS AND RESULTS Myocyte contractility, Ca(2+) handling and excitation-contraction coupling were studied in isolated cardiomyocytes from wild-type and GRK2 knockout (GRK2KO) mice without (sham) or with myocardial infarction (MI). In cardiac myocytes isolated from unstressed wild-type and GRK2KO hearts, myocyte contractions and Ca(2+) transients were similar, but GRK2KO myocytes had lower sarcoplasmic reticulum (SR) Ca(2+) content because of increased sodium-Ca(2+) exchanger activity and inhibited SR Ca(2+) ATPase by local protein kinase A-mediated activation of phosphodiesterase 4 resulting in hypophosphorylated phospholamban. This Ca(2+) handling phenotype is explained by a higher fractional SR Ca(2+) release induced by increased L-type Ca(2+) channel currents. After β-adrenergic stimulation, GRK2KO myocytes revealed significant increases in contractility and Ca(2+) transients, which were not mediated through cardiac L-type Ca(2+) channels but through an increased SR Ca(2+). Interestingly, post-MI GRK2KO mice showed better cardiac function than post-MI control mice, which is explained by an improved Ca(2+) handling phenotype. The SR Ca(2+) content was better maintained in post-MI GRK2KO myocytes than in post-MI control myocytes because of better-maintained L-type Ca(2+) channel current density and no increase in sodium-Ca(2+) exchanger in GRK2KO myocytes. An L-type Ca(2+) channel blocker, verapamil, reversed some beneficial effects of GRK2KO. CONCLUSIONS These data argue for novel differential regulation of L-type Ca(2+) channel currents and SR load by GRK2. G-protein-coupled receptor kinase 2 ablation represents a novel beneficial Ca(2+) handling phenotype resisting adverse remodeling after MI.
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Affiliation(s)
- Philip W Raake
- Department of Internal Medicine III, Cardiology, University of Heidelberg, Germany.
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Rottlaender D, Matthes J, Vatner SF, Seifert R, Herzig S. Functional adenylyl cyclase inhibition in murine cardiomyocytes by 2'(3')-O-(N-methylanthraniloyl)-guanosine 5'-[gamma-thio]triphosphate. J Pharmacol Exp Ther 2007; 321:608-15. [PMID: 17284671 DOI: 10.1124/jpet.106.118422] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Beta1-adrenergic receptor activation stimulates cardiac L-type Ca2+ channels via adenylyl cyclases (ACs), with AC5 and AC6 being the most important cardiac isoforms. Recently, we have identified 2'(3')-O-(N-methylanthraniloyl)-guanosine 5'-[gamma-thio-]triphosphate (MANT-GTPgammaS) as a potent competitive AC inhibitor. Intriguingly, MANT-GTPgammaS inhibits AC5 and -6 more potently than other cyclases. These data prompted us to study the effects of MANT-GTPgammaS on L-type Ca2+ currents (ICa,L) in ventricular myocytes of wild-type (WT) and AC5-deficient (AC5-/-) mice by whole-cell recordings. In wild-type myocytes, MANT-GTPgammaS attenuated ICa,L stimulation following isoproterenol application in a concentration-dependent manner (control, +77+/-13%; 100 nM MANT-GTPgammaS, +43+/-6%; 1 microM MANT-GTPgammaS, +21+/-9%; p<0.05). The leftward shift of current-voltage curves was abolished by 1 microM but not by 100 nM MANT-GTPgammaS. In myocytes from AC5-/- mice, the residual stimulation of ICa,L was not further attenuated by the nucleotide, indicating AC5 to be the major AC isoform mediating acute beta-adrenergic stimulation in WT mice. Interestingly, basal ICa,L was lowered by 1 microM but not by 100 nM MANT-GTPgammaS. The decrease was less pronounced in myocytes from AC5-/- mice compared with wild types (-23+/-1 versus -40+/-7%), indicating basal ICa,L to be partly driven by AC5. Collectively, we found a concentration-dependent inhibition of ICa,L by MANT-GTPgammaS, both under basal conditions and following beta-adrenergic stimulation. Comparison of data from wild-type and AC5-deficient mice indicates that AC5 plays a major role in ICa,L activation and that MANT-GTPgammaS predominantly acts via AC5 inhibition.
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Affiliation(s)
- Dennis Rottlaender
- Department of Pharmacology, Center for Molecular Medicine, University of Cologne, Gleueler Str. 24, D-50931 Köln, Germany
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