Dual Specificity Phosphatase 4 Mediates Cardiomyopathy Caused by Lamin A/C (LMNA) Gene Mutation

Abstract

Mutations in LMNA gene cause cardiomyopathy, for which mechanistic insights are lacking. Dusp4 expression is enhanced in hearts with LMNA cardiomyopathy, and its overexpression in mice causes it by activating AKT-mTOR signaling that impairs autophagy. Dusp4 causes cardiac dysfunction and may contribute to the development of LMNA cardiomyopathy. Revealing pathogenic mechanisms of LMNA cardiomyopathy is essential for the development of mechanism-based therapies. Mutations in the lamin A/C gene (LMNA) cause a diverse spectrum of diseases, the most common of which is dilated cardiomyopathy often with skeletal muscular dystrophy. Lamin A and C are fundamental components of the nuclear lamina, a dynamic meshwork of intermediate filaments lining the nuclear envelope inner membrane. Prevailing evidence suggests that the nuclear envelope functions as a signaling node and that abnormality in the nuclear lamina leads to dysregulated signaling pathways that underlie disease pathogenesis. We previously showed that activated ERK1/2 in hearts of a mouse model of LMNA cardiomyopathy (Lmna(H222P/H222P) mice) contributes to disease, but the complete molecular pathogenesis remains poorly understood. Here we uncover a pathogenic role of dual specificity phosphatase 4 (Dusp4), which is transcriptionally induced by ERK1/2. Dusp4 is highly expressed in the hearts of Lmna(H222P/H222P) mice, and transgenic mice with cardiac-selective overexpression of Dusp4 display heart dysfunction similar to LMNA cardiomyopathy. In both primary tissue and cell culture models, overexpression of Dusp4 positively regulates AKT-mTOR signaling, resulting in impaired autophagy. These findings identify a pathogenic role of Dusp4 in LMNA cardiomyopathy.