Cardiomyocyte-produced miR-339-5p mediates pathology in Duchenne muscular dystrophy cardiomyopathy

Abstract

Duchenne muscular dystrophy (DMD) is an X-linked genetic disease characterized by severe, progressive muscle wasting. Cardiomyopathy has emerged as a leading cause of death in patients with DMD. The mechanisms contributing to DMD cardiac disease remain under investigation and specific therapies available are lacking. Our prior work has shown that DMD-iPSC derived cardiomyocytes (DMD-iCMs) are vulnerable to oxidative stress injury and chronic exposure to DMD secreted exosomes impaired the cell’s ability to protect against stress. In this study, we sought to examine a mechanism by which DMD cardiac exosomes impair cellular response through altering important stress-responsive genes in the recipient cells. Here, we report that DMD-iCMs secrete exosomes containing altered microRNA (miR) profiles in comparison to healthy controls. In particular, miR-339-5p was upregulated in DMD-iCMs, DMD exosomes, and in mdx mouse cardiac tissue. Restoring dystrophin in DMD-iCMs improved the cellular response to stress and was associated with downregulation of miR-339-5p, suggesting that it is disease-specific. Knockdown of miR-339-5p was associated with increased expression of MDM2, GSK3A and MAP2K3, which are genes involved in important stress-responsive signaling pathways. Finally, knockdown of miR-339-5p led to mitochondrial protection and a reduction in cell death in DMD-iCMs, indicating miR-339-5p is involved in direct modulation of stress-responsiveness. Together, these findings identify a potential mechanism by which exosomal miR-339-5p may be modulating cell signaling pathways which are important for robust stress responses. Additionally, these exosomal miRs may provide important disease specific targets for future therapeutic advancements for the management and diagnosis of DMD cardiomyopathy.

Selective Delivery to Cardiac Muscle Cells Using Cell-Specific Aptamers

“…A direct comparison between wild-type CM isolations and mdx CMs suggested some differences in the recovery yields. This is most likely correlated to the disease (DMD), where the decrease in dystrophin protein (a structural and protective muscle protein) renders mdx CMs more fragile, vulnerable to stress, and easily damaged [ 35 ].…”

MicroRNAs in Dystrophinopathy

“…Downregulation of miR-339-5p directly modulated stress-response genes and reduced cardiomyocyte death in DMD-iCMs. These data indicate a pathological role of elevated miR-339-5p in DMD cardiomyocytes [59]. Serum miRNAs in disease carriers: Even without skeletal muscle symptoms, heart symptoms often occur in female DMD/BMD carriers for the asymptomatic form with mild abnormalities to progressive heart failure [60] and dilated cardiomyopathy [61], which may require heart transplantation [62].…”

“…Downregulation of miR-339-5p directly modulated stress-response genes and reduced cardiomyocyte death in DMD-iCMs. These data indicate a pathological role of elevated miR-339-5p in DMD cardiomyocytes [ 59 ].…”

The Role of MicroRNA in the Pathogenesis of Duchenne Muscular Dystrophy

“…[63] miR-339-5p DMD-derived cardiomyocytes secrete exosomes containing miR-339-5p that impairs the response of other cardiac cells to stress. [76] miR-448-3p Downregulation of miR-448-3p, which is observed in dystrophic hearts, was associated with the induction of fibrosis and cardiac remodelling. [77] miR-25 Suppression of overexpressed miR-25 in DMD animal models was associated with improved myocyte contractility and enhanced survival.…”