miR-181c Regulates the Mitochondrial Genome, Bioenergetics, and Propensity for Heart Failure In Vivo

Abstract

MicroRNAs (miRNAs) are small non-coding RNAs, which inhibit the stability and/or translation of a mRNA. miRNAs have been found to play a powerful role in various cardiovascular diseases. Recently, we have demonstrated that a microRNA (miR-181c) can be encoded in the nucleus, processed to the mature form in the cytosol, translocated into the mitochondria, and ultimately can regulate mitochondrial gene expression. However the in vivo impact of miR-181c is unknown. Here we report an in-vivo method for administration of miR-181c in rats, which leads to reduced exercise capacity and signs of heart failure, by targeting the 3′-end of mt-COX1 (cytochrome c oxidase subunit 1). We cloned miR-181c and packaged it in lipid-based nanoparticles for systemic delivery. The plasmid DNA complexed nanovector shows no apparent toxicity. We find that the mRNA levels of mitochondrial complex IV genes in the heart, but not any other mitochondrial genes, are significantly altered with miR-181c overexpression, suggesting selective mitochondrial complex IV remodeling due to miR-181c targeting mt-COX1. Isolated heart mitochondrial studies showed significantly altered O2-consumption, ROS production, matrix calcium, and mitochondrial membrane potential in miR-181c-treated animals. For the first time, this study shows that miRNA delivered to the heart in-vivo can lead to cardiac dysfunction by regulating mitochondrial genes.

Roles of the canonical myomiRs miR-1, -133 and -206 in cell development and disease

“…The reduced mtCOX1 causes mitochondrial complex IV remodelling, resulting in increased mt respiration and increased ROS generation. Recently, Das et al [55] (2014) used cationic nanoparticles to deliver miR181c into rat cardiac mitochondria in vivo, causing cardiac dysfunction and a tendency to develop heart failure. Taken together, these studies reveal important new miRmediated regulatory pathways in muscle mitochondria involving direct manipulation of mitochondrial gene expression by cytosolic miRNAs, including by a myomiR.…”

“…Results in reduced capacity for strenuous exercise and evidence of heart failure Rat cardiac muscle [55] Carvedilol, a β-adrenergic blocker Induces upregulation of miR-133 Cytoprotective effects against cardiomyocyte apoptosis…”

Exploring the mitochondrial microRNA import pathway through Polynucleotide Phosphorylase (PNPase)

“…The association of a miRNA with the RNA-induced silencing complex (RISC) has been shown in the cytoplasm, with the Argonaute (AGO) family proteins functioning to help in miRNA repression through the inhibition of protein synthesis when bound to the 3′-untranslated region of the mRNA [6,39]. A variety of groups, including our own, has also indicated the presence of miRNA in the mitochondria [3,5,13–15,27,28,50,55,83–85, 89,98]. MiRNA species have the ability to target mRNA transcripts produced by the mitochondrial genome in the mitochondrion to control mRNA stability and degradation [27,28,33].…”

Integrative analysis of competing endogenous RNA networks reveals the functional lncRNAs in heart failure

“…For example, miR‐181c targeted to 3′UTR of the mRNA of a mitochondrial gene, mt‐COX1. Overexpression of miR‐181c could decrease mt‐COX1 protein expression, increasing production of reactive oxygen species in heart failure 31. Mir‐148 was a repressor of NF‐kB signalling, playing roles in cardiac injury 32.…”

“…MiRNAs that mediated dysregulated ceRNA interactions were extracted, which have been demonstrated to play crucial roles in the pathology of heart failure. For example, overexpression of miR‐181c could decrease mt‐COX1 protein expression, increasing production of reactive oxygen species in heart failure 31. MiR‐34 family was demonstrated to attenuate pathological cardiac remodelling and improve heart function.…”