Decreased WNT/β-catenin signalling contributes to the pathogenesis of dilated cardiomyopathy caused by mutations in the lamin a/C gene

Cardiomyopathy caused by lamin A/C gene (LMNA) mutations (hereafter referred as LMNA cardiomyopathy) is characterized by cardiac conduction abnormalities and left ventricular systolic dysfunction predisposing to heart failure. Previous cardiac transcriptional profiling of LmnaH222P/H222P mouse, a small animal model of LMNA cardiomyopathy, suggested decreased WNT/b-catenin signalling.We confirmed decreased WNT/b-catenin signalling in the hearts of these mice by demonstrating decreased b-catenin andWNTproteins. This was correlated with increased expression of soluble Frizzled-related proteins that modulate the WNT/b-catenin signalling pathway. Hearts of LmnaH222P/H222P mice also demonstrated lowered expression of the gap junction connexin 43. Activation of WNT/b-catenin activity with 6-bromoindirubin-3’-oxime improved cardiac con- tractility and ameliorated intraventricular conduction defects in LmnaH222P/H222P mice, which was associated with increased expression of myocardial connexin 43. These results indicate that decreased WNT/b-catenin contributes to the pathophysiol- ogy of LMNA cardiomyopathy and that drugs activating b-catenin may be beneficial in affected individuals.