Oxidized CaMKII (Ca 2+/Calmodulin-Dependent Protein Kinase II) Is Essential for Ventricular Arrhythmia in a Mouse Model of Duchenne Muscular Dystrophy

Circ Arrhythm Electrophysiol. 2018 Apr;11(4):e005682. doi: 10.1161/CIRCEP.117.005682.

Abstract

Background: Duchenne muscular dystrophy patients are prone to ventricular arrhythmias, which may be caused by abnormal calcium (Ca2+) homeostasis and elevated reactive oxygen species. CaMKII (Ca2+/calmodulin-dependent protein kinase II) is vital for normal Ca2+ homeostasis, but excessive CaMKII activity contributes to abnormal Ca2+ homeostasis and arrhythmias in cardiomyocytes. Reactive oxygen species induce CaMKII to become autonomously active. We hypothesized that genetic inhibition of CaMKII oxidation (ox-CaMKII) in a mouse model of Duchenne muscular dystrophy can alleviate abnormal Ca2+ homeostasis, thus, preventing ventricular arrhythmia. The objective of this study was to test if selective loss of ox-CaMKII affects ventricular arrhythmias in the mdx mouse model of Duchenne muscular dystrophy.

Methods and results: 5-(6)-Chloromethyl-2,7-dichlorodihydrofluorescein diacetate staining revealed increased reactive oxygen species production in ventricular myocytes isolated from mdx mice, which coincides with elevated ventricular ox-CaMKII demonstrated by Western blotting. Genetic inhibition of ox-CaMKII by knockin replacement of the regulatory domain methionines with valines (MM-VV [CaMKII M281/282V]) prevented ventricular tachycardia in mdx mice. Confocal calcium imaging of ventricular myocytes isolated from mdx:MM-VV mice revealed normalization of intracellular Ca2+ release events compared with cardiomyocytes from mdx mice. Abnormal action potentials assessed by optical mapping in mdx mice were also alleviated by genetic inhibition of ox-CaMKII. Knockout of the NADPH oxidase regulatory subunit p47 phox normalized elevated ox-CaMKII, repaired intracellular Ca2+ homeostasis, and rescued inducible ventricular arrhythmias in mdx mice.

Conclusions: Inhibition of reactive oxygen species or ox-CaMKII protects against proarrhythmic intracellular Ca2+ handling and prevents ventricular arrhythmia in a mouse model of Duchenne muscular dystrophy.

Keywords: Duchenne muscular dystrophy; action potential; arrhythmia; calcium/calmodulin-dependent protein kinase II; reactive oxygen species.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Action Potentials
  • Animals
  • Arrhythmias, Cardiac / enzymology
  • Arrhythmias, Cardiac / etiology*
  • Arrhythmias, Cardiac / physiopathology
  • Arrhythmias, Cardiac / prevention & control
  • Calcium / metabolism
  • Calcium Signaling
  • Calcium-Calmodulin-Dependent Protein Kinase Type 2 / genetics
  • Calcium-Calmodulin-Dependent Protein Kinase Type 2 / metabolism*
  • Disease Models, Animal
  • Heart Rate
  • Heart Ventricles / enzymology*
  • Heart Ventricles / physiopathology
  • Mice, Inbred mdx
  • Mice, Transgenic
  • Muscular Dystrophy, Duchenne / complications*
  • Muscular Dystrophy, Duchenne / enzymology
  • Muscular Dystrophy, Duchenne / physiopathology
  • NADPH Oxidase 2 / metabolism
  • Oxidation-Reduction
  • Oxidative Stress
  • Reactive Oxygen Species / metabolism

Substances

  • Reactive Oxygen Species
  • Cybb protein, mouse
  • NADPH Oxidase 2
  • Calcium-Calmodulin-Dependent Protein Kinase Type 2
  • Calcium