Activation of MAPK pathways links LMNA mutations to cardiomyopathy in Emery-Dreifuss muscular dystrophy
Antoine Muchir, … , Gisèle Bonne, Howard J. Worman
Antoine Muchir, … , Gisèle Bonne, Howard J. Worman
Published May 1, 2007
Citation Information: J Clin Invest. 2007;117(5):1282-1293. https://doi.org/10.1172/JCI29042.
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Research Article Cardiology

Activation of MAPK pathways links LMNA mutations to cardiomyopathy in Emery-Dreifuss muscular dystrophy

Abstract

Mutations in LMNA, which encodes nuclear Lamins A and C cause diseases affecting various organs, including the heart. We have determined the effects of an Lmna H222P mutation on signaling pathways involved in the development of cardiomyopathy in a knockin mouse model of autosomal dominant Emery-Dreifuss muscular dystrophy. Analysis of genome-wide expression profiles in hearts using Affymetrix GeneChips showed statistically significant differences in expression of genes in the MAPK pathways at the incipience of the development of clinical disease. Using real-time PCR, we showed that activation of MAPK pathways preceded clinical signs or detectable molecular markers of cardiomyopathy. In heart tissue and isolated cardiomyocytes, there was activation of MAPK cascades and downstream targets, implicated previously in the pathogenesis of cardiomyopathy. Expression of H222P Lamin A in cultured cells activated MAPKs and downstream target genes. Activation of MAPK signaling by mutant A-type lamins could be a cornerstone in the development of heart disease in autosomal dominant Emery-Dreifuss muscular dystrophy.

Authors

Antoine Muchir, Paul Pavlidis, Valérie Decostre, Alan J. Herron, Takuro Arimura, Gisèle Bonne, Howard J. Worman

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Figure 7

Expression of H222P Lamin A in transfected Cos-7 and C2C12 cells leads to increased phosphorylation and enhanced nuclear translocation of ERK1/2.

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Expression of H222P Lamin A in transfected Cos-7 and C2C12 cells leads t...
(A and B) Effect of H222P Lamin A expression on levels of pERK1/2 in transfected Cos-7 (A) and C2C12 (B) cells. Immunoblotting with pERK1/2 Ab and total ERK1/2 Ab was performed. Data are shown as mean ± SD of 11 (A) and 7 (B) samples per group (*P < 0.05). Significance of the results was determined using paired Student’s t test (for parametric data) and a Wilcoxon rank-sum test (for nonparametric data). Immunoblotting with GFP Ab is shown to demonstrate expression of proteins encoded by transfected plasmids. Immunoblotting with β-actin Ab was used as a loading control. (C and D) Effect of H222P Lamin A on nuclear translocation of pERK1/2 in transfected Cos-7 (C) and C2C12 (D) cells. Representative photomicrographs are shown for nontransfected (NT) cells, transfected cells expressing a GFP fusion of wild-type Lamin A, and transfected cells expressing a GFP fusion of Lamin A with the H222P amino acid substitution. Arrowheads show enhanced nuclear localization of pERK1/2 in cells expressing GFP H222P Lamin A. Scale bars: 10 μm. (E and F) Percentage of Cos-7 (E) and C2C12 (F) cells with pERK1/2 primarily in the nucleus. Nontransfected cells, transfected cells expressing a GFP fusion of wild-type Lamin A, and transfected cells expressing a GFP fusion of Lamin A with the H222P aa substitution were randomly counted and scored for nuclear pERK1/2 (see arrowheads in C for example). Transfected cells were determined by presence of GFP signal. Values are mean ± SD for 200 cells per group (*P < 0.05). The person counting the cells was blinded as to which protein was expressed.