Connexin-43 Restoration Alleviates Desmosomal Arrhythmogenic Cardiomyopathy

Arrhythmogenic cardiomyopathy (ACM) is a fatal genetic heart disease primarily caused by mutations in desmosomal genes, leading to impaired cell-cell adhesion, ventricular arrhythmias, and progressive heart failure. Although gene therapy for specific ACM populations shows promise, it remains unclear whether mutation-agnostic pathways dysregulated across desmosomal mutations could be exploited for therapeutic intervention in this genetically broad and severe population. The reduction in expression of the ventricular gap junction protein Cx43 (connexin-43) is a common molecular alteration underlying desmosomal junctional deficits and arrhythmias, suggesting a potential common underlying mechanism and a therapeutic target for ACM. We hypothesized that restoration of Cx43 expression could be a mutation-agnostic intervention for ACM.

We exploited adeno-associated-viral-mediated gene therapy to restore the gap junction protein, Cx43, in genetic mouse models and human stem cell models of ACM, harboring loss or mutations in desmosomal genes, including Dsp (desmoplakin), PKP2 (plakophilin-2), and DSG2 (desmoglein-2).

Administration of AAV-Cx43 (adeno-associated-viral-mediated connexin-43) gene therapy alleviated the severe biventricular dilatation, contractile dysfunction, and arrhythmias, while prolonging lifespan in 2 severe desmosomal ACM mouse models, either harboring Dsp loss and a prevalent human PKP2 mutation. Viral-mediated restoration of Cx43 could also alleviate physiological deficits in ACM human induced pluripotent stem cell-derived cardiomyocytes harboring PKP2 and DSG2 mutations. Mechanistically, Cx43 targets desmosomal protein expression and relocalization to the cell junction to support their mechanical stabilization and coupling.

By using mouse and human models of desmosomal ACM harboring different mutational backgrounds, we show the sufficiency of Cx43 gene therapy and its restoration to modify and alleviate ACM deficits. These data suggest that noncanonical functions of Cx43, including mechanical modulation and reassembly of the desmosome, are a therapeutic target with the potential to treat diverse ACM populations.