S-nitrosylation of connexin43 hemichannels elicits cardiac stress–induced arrhythmias in Duchenne muscular dystrophy mice
Mauricio A. Lillo, Eric Himelman, Natalia Shirokova, Lai-Hua Xie, Diego Fraidenraich, Jorge E. Contreras
Mauricio A. Lillo, Eric Himelman, Natalia Shirokova, Lai-Hua Xie, Diego Fraidenraich, Jorge E. Contreras
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Research Article Muscle biology

S-nitrosylation of connexin43 hemichannels elicits cardiac stress–induced arrhythmias in Duchenne muscular dystrophy mice

Abstract

Patients with Duchenne muscular dystrophy (DMD) commonly present with severe ventricular arrhythmias that contribute to heart failure. Arrhythmias and lethality are also consistently observed in adult Dmdmdx mice, a mouse model of DMD, after acute β-adrenergic stimulation. These pathological features were previously linked to aberrant expression and remodeling of the cardiac gap junction protein connexin43 (Cx43). Here, we report that remodeled Cx43 protein forms Cx43 hemichannels in the lateral membrane of Dmdmdx cardiomyocytes and that the β-adrenergic agonist isoproterenol (Iso) aberrantly activates these hemichannels. Block of Cx43 hemichannels or a reduction in Cx43 levels (using Dmdmdx Cx43+/– mice) prevents the abnormal increase in membrane permeability, plasma membrane depolarization, and Iso-evoked electrical activity in these cells. Additionally, Iso treatment promotes nitric oxide (NO) production and S-nitrosylation of Cx43 hemichannels in Dmdmdx heart. Importantly, inhibition of NO production prevents arrhythmias evoked by Iso. We found that NO directly activates Cx43 hemichannels by S-nitrosylation of cysteine at position 271. Our results demonstrate that opening of remodeled and S-nitrosylated Cx43 hemichannels plays a key role in the development of arrhythmias in DMD mice and that these channels may serve as therapeutic targets to prevent fatal arrhythmias in patients with DMD .

Authors

Mauricio A. Lillo, Eric Himelman, Natalia Shirokova, Lai-Hua Xie, Diego Fraidenraich, Jorge E. Contreras

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Figure 4

Blockade of NO production prevents Cx43 hemichannel–mediated TA and arrhythmias in Dmdmdx mice.

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Blockade of NO production prevents Cx43 hemichannel–mediated TA and arrh...
(A) Representative action potential traces of WT and Dmdmdx isolated cardiomyocytes. Cells were stimulated with 1 μM Iso in the presence of 100 μM l-NAME. Arrow indicates electrical stimulation. (B) Quantification of TA induced by Iso observed in A. The number in parentheses indicates the n value. Comparisons between groups were made using 2-way ANOVA plus Tukey’s post hoc test; *P < 0.05. (C) Resting membrane potential of WT and Dmdmdx cardiomyocytes. Comparisons between groups were made using 2-way ANOVA plus Tukey’s post hoc test. (D) Representative ECG traces of 5- to 6-month-old WT and Dmdmdx mice that were previously treated or not with 2 mM l-NAME (an unspecific NOS blocker) via drinking water. ECG baseline and ECG after Iso treatment (5 mg/kg IP) are shown for comparison. (E) Arrhythmia score based on predetermined scale: 0, no arrhythmias; 1, single premature ventricular contractions (PVCs); 2, double PVCs; 3, triple PVCs or nonsustained ventricular tachycardia (VT); 4, sustained VT or atrioventricular (AV) block; and 5, death. *P < 0.0001 versus WT; †P < 0.0001 versus Dmdmdx l-NAME. The number in parentheses indicates the n value. Statistical significance determined by 1-way ANOVA plus Tukey’s post hoc test.