Calcium/calmodulin-dependent protein kinase II (CaMKII) inhibition ameliorates arrhythmias elicited by junctin ablation under stress conditions

Christos Tzimas, John Terrovitis, Stephan E. Lehnart, Evangelia G. Kranias, Despina Sanoudou

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

Background Aberrant calcium signaling is considered one of the key mechanisms contributing to arrhythmias, especially in the context of heart failure. In human heart failure, there is significant down-regulation of the sarcoplasmic reticulum (SR) protein junctin, and junctin deficiency in mice is associated with stress-induced arrhythmias. Objective The purpose of this study was to determine whether the increased SR Ca<sup>2+</sup> leak and arrhythmias associated with junctin ablation may be associated with increased calcium/calmodulin-dependent protein kinase II (CaMKII) activity and phosphorylation of the cardiac ryanodine receptor (RyR2) and whether pharmacologic inhibition of CaMKII activity may prevent these arrhythmias. Methods Using a combination of biochemical, cellular, and in vivo approaches, we tested the ability of KN-93 to reverse aberrant CaMKII phosphorylation of RyR2. Specifically, we performed protein phosphorylation analysis, in vitro cardiomyocyte contractility and Ca<sup>2+</sup> kinetics, and in vivo ECG analysis in junctin-deficient mice. Results In the absence of junctin, RyR2 channels displayed CaMKII-dependent hyperphosphorylation. Notably, CaMKII inhibition by KN-93 reduced the in vivo incidence of stress-induced ventricular tachycardia by 65% in junctin null mice. At the cardiomyocyte level, KN-93 reduced the percentage of junctin null cells exhibiting spontaneous Ca<sup>2+</sup> aftertransients and aftercontractions under stress conditions by 35% and 37%, respectively. At the molecular level, KN-93 blunted the CaMKII-mediated hyperphosphorylation of RyR2 and phospholamban under stress conditions. Conclusion Our data suggest that CaMKII inhibition is effective in preventing arrhythmogenesis in the setting of junctin ablation through modulation of both SR Ca<sup>2+</sup> release and uptake. Thus, it merits further investigation as promising molecular therapy.

Original languageEnglish
Pages (from-to)1599-1610
Number of pages12
JournalHeart Rhythm
Volume12
Issue number7
DOIs
Publication statusPublished - 1 Jul 2015
Externally publishedYes

Fingerprint

Calcium-Calmodulin-Dependent Protein Kinase Type 2
Calcium-Calmodulin-Dependent Protein Kinases
Cardiac Arrhythmias
Ryanodine Receptor Calcium Release Channel
Sarcoplasmic Reticulum
Phosphorylation
Cardiac Myocytes
Heart Failure
Null Lymphocytes
Calcium Signaling
Ventricular Tachycardia
Electrocardiography
Proteins
Down-Regulation
KN 93
Incidence

Keywords

  • Arrhythmia
  • Calcium/calmodulin-dependent protein kinase II
  • Isoproterenol
  • Junctin
  • Ryanodine receptor

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

Cite this

Calcium/calmodulin-dependent protein kinase II (CaMKII) inhibition ameliorates arrhythmias elicited by junctin ablation under stress conditions. / Tzimas, Christos; Terrovitis, John; Lehnart, Stephan E.; Kranias, Evangelia G.; Sanoudou, Despina.

In: Heart Rhythm, Vol. 12, No. 7, 01.07.2015, p. 1599-1610.

Research output: Contribution to journalArticle

Tzimas, Christos ; Terrovitis, John ; Lehnart, Stephan E. ; Kranias, Evangelia G. ; Sanoudou, Despina. / Calcium/calmodulin-dependent protein kinase II (CaMKII) inhibition ameliorates arrhythmias elicited by junctin ablation under stress conditions. In: Heart Rhythm. 2015 ; Vol. 12, No. 7. pp. 1599-1610.
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abstract = "Background Aberrant calcium signaling is considered one of the key mechanisms contributing to arrhythmias, especially in the context of heart failure. In human heart failure, there is significant down-regulation of the sarcoplasmic reticulum (SR) protein junctin, and junctin deficiency in mice is associated with stress-induced arrhythmias. Objective The purpose of this study was to determine whether the increased SR Ca2+ leak and arrhythmias associated with junctin ablation may be associated with increased calcium/calmodulin-dependent protein kinase II (CaMKII) activity and phosphorylation of the cardiac ryanodine receptor (RyR2) and whether pharmacologic inhibition of CaMKII activity may prevent these arrhythmias. Methods Using a combination of biochemical, cellular, and in vivo approaches, we tested the ability of KN-93 to reverse aberrant CaMKII phosphorylation of RyR2. Specifically, we performed protein phosphorylation analysis, in vitro cardiomyocyte contractility and Ca2+ kinetics, and in vivo ECG analysis in junctin-deficient mice. Results In the absence of junctin, RyR2 channels displayed CaMKII-dependent hyperphosphorylation. Notably, CaMKII inhibition by KN-93 reduced the in vivo incidence of stress-induced ventricular tachycardia by 65{\%} in junctin null mice. At the cardiomyocyte level, KN-93 reduced the percentage of junctin null cells exhibiting spontaneous Ca2+ aftertransients and aftercontractions under stress conditions by 35{\%} and 37{\%}, respectively. At the molecular level, KN-93 blunted the CaMKII-mediated hyperphosphorylation of RyR2 and phospholamban under stress conditions. Conclusion Our data suggest that CaMKII inhibition is effective in preventing arrhythmogenesis in the setting of junctin ablation through modulation of both SR Ca2+ release and uptake. Thus, it merits further investigation as promising molecular therapy.",
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T1 - Calcium/calmodulin-dependent protein kinase II (CaMKII) inhibition ameliorates arrhythmias elicited by junctin ablation under stress conditions

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AU - Kranias, Evangelia G.

AU - Sanoudou, Despina

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N2 - Background Aberrant calcium signaling is considered one of the key mechanisms contributing to arrhythmias, especially in the context of heart failure. In human heart failure, there is significant down-regulation of the sarcoplasmic reticulum (SR) protein junctin, and junctin deficiency in mice is associated with stress-induced arrhythmias. Objective The purpose of this study was to determine whether the increased SR Ca2+ leak and arrhythmias associated with junctin ablation may be associated with increased calcium/calmodulin-dependent protein kinase II (CaMKII) activity and phosphorylation of the cardiac ryanodine receptor (RyR2) and whether pharmacologic inhibition of CaMKII activity may prevent these arrhythmias. Methods Using a combination of biochemical, cellular, and in vivo approaches, we tested the ability of KN-93 to reverse aberrant CaMKII phosphorylation of RyR2. Specifically, we performed protein phosphorylation analysis, in vitro cardiomyocyte contractility and Ca2+ kinetics, and in vivo ECG analysis in junctin-deficient mice. Results In the absence of junctin, RyR2 channels displayed CaMKII-dependent hyperphosphorylation. Notably, CaMKII inhibition by KN-93 reduced the in vivo incidence of stress-induced ventricular tachycardia by 65% in junctin null mice. At the cardiomyocyte level, KN-93 reduced the percentage of junctin null cells exhibiting spontaneous Ca2+ aftertransients and aftercontractions under stress conditions by 35% and 37%, respectively. At the molecular level, KN-93 blunted the CaMKII-mediated hyperphosphorylation of RyR2 and phospholamban under stress conditions. Conclusion Our data suggest that CaMKII inhibition is effective in preventing arrhythmogenesis in the setting of junctin ablation through modulation of both SR Ca2+ release and uptake. Thus, it merits further investigation as promising molecular therapy.

AB - Background Aberrant calcium signaling is considered one of the key mechanisms contributing to arrhythmias, especially in the context of heart failure. In human heart failure, there is significant down-regulation of the sarcoplasmic reticulum (SR) protein junctin, and junctin deficiency in mice is associated with stress-induced arrhythmias. Objective The purpose of this study was to determine whether the increased SR Ca2+ leak and arrhythmias associated with junctin ablation may be associated with increased calcium/calmodulin-dependent protein kinase II (CaMKII) activity and phosphorylation of the cardiac ryanodine receptor (RyR2) and whether pharmacologic inhibition of CaMKII activity may prevent these arrhythmias. Methods Using a combination of biochemical, cellular, and in vivo approaches, we tested the ability of KN-93 to reverse aberrant CaMKII phosphorylation of RyR2. Specifically, we performed protein phosphorylation analysis, in vitro cardiomyocyte contractility and Ca2+ kinetics, and in vivo ECG analysis in junctin-deficient mice. Results In the absence of junctin, RyR2 channels displayed CaMKII-dependent hyperphosphorylation. Notably, CaMKII inhibition by KN-93 reduced the in vivo incidence of stress-induced ventricular tachycardia by 65% in junctin null mice. At the cardiomyocyte level, KN-93 reduced the percentage of junctin null cells exhibiting spontaneous Ca2+ aftertransients and aftercontractions under stress conditions by 35% and 37%, respectively. At the molecular level, KN-93 blunted the CaMKII-mediated hyperphosphorylation of RyR2 and phospholamban under stress conditions. Conclusion Our data suggest that CaMKII inhibition is effective in preventing arrhythmogenesis in the setting of junctin ablation through modulation of both SR Ca2+ release and uptake. Thus, it merits further investigation as promising molecular therapy.

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KW - Ryanodine receptor

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