Abstract 18731: Prevention of Protease 2a-Mediated Cleavage of Dystrophin Inhibits Disruption of the Sarcolemma and Enteroviral-Mediated Cardiomyopathy
Introduction: Coxsackievirus (CV) is a member of the enteroviral genus of the picornavirus family and is known to be an important cause of myocarditis and heart failure in children and adults. Enteroviral protease 2A cleaves the viral polyprotein and a small number of host cell proteins such as the cytoskeletal protein, dystrophin, and the eukaryotic translation initiation factor (eIF4G)-1 and -2. Genetic deficiency of dystrophin causes cardiomyopathy in Duchenne muscular dystrophy and increases susceptibility to enteroviral myocarditis. However, the importance of protease 2A-mediated cleavage of dystrophin and disruption of the sarcolemma is not known. We hypothesized that cleavage of dystrophin by protease 2A is important in viral propagation, enteroviral-mediated cytopathic effects, and the development of cardiomyopathy following enteroviral infection.
Methods and Results: The current studies were designed to test whether inhibition of dystrophin cleavage alters CVB3-mediated myocarditis. In order to address this hypothesis, we knocked-in a mutation at the protease 2A-cleavage site of the dystrophin gene, thus inhibiting only the cleavage of dystrophin following CVB3 infection. Mice expressing cleavage-resistant dystrophin were less susceptible to CVB3 infection as indicated by a significant decrease in the cardiac virus titer eight days post-CVB3 infection. Sarcolemmal integrity, as measured by Evan’s blue dye uptake and Von Kossa staining, was also significantly improved in cleavage -resistant mice. In addition, myocarditis was decreased in infected knock-in mice compared to wild-type infected littermate controls. Also, prevention of dystrophin cleavage in protease 2A expressing transgenic mice markedly inhibited the protease 2A-induced myocytopathic effect.
Conclusions: These findings indicate that disruption of the sarcolemma by protease 2A-mediated cleavage of dystrophin can have a critical role in viral propagation, enteroviral-mediated cytopathic effects, and the development of cardiomyopathy in control mice. These findings demonstrate that alterations in the dystrophin-glycoprotein complex which alter sarcolemmal integrity could contribute to susceptibility to virus infection.
- © 2013 by American Heart Association, Inc.