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Small RNA sequencing of mouse muscle and heart samples after small hairpin RNA delivery

ABSTRACT: RNA interference (RNAi) is a promising gene therapy strategy for targeting dominant mutations. This therapy leverages small hairpin RNAs (shRNAs) to knock down gene expression; however, delivery of too much shRNA can disrupt the processing of endogenous microRNAs (miRNAs), and lead to toxicity. In this study, we sought to understand the effect that excessive shRNAs have on muscle miRNAs by transducing several constructs in mice and performing small RNA sequencing on their muscle and liver tissues. We found that shRNA expression was highest in the heart, and that when shRNAs accumulated to about 27% of total small RNAs, mice experienced substantial cardiomyopathy. At this level in the heart, shRNAs in other muscle tissues were only ~1.8-7.6% of total miRNAs. Regardless of treatment, the predominant heart microRNAs remained stable across samples, while the lower-expressed miR-451 – one of the only microRNAs processed in a Dicer-independent manner – changed in direct correlation with shRNA level and toxicity. Our data suggest that certain muscle miRNAs compete with exogenous shRNAs, leading to the observed cardiomyopathy, and that the mechanism of cardiotoxicity in these mice in response shRNA treatment was in contrast to what has been previously shown in the liver. Quantifying microRNA profiles after excessive shRNA delivery illuminates the host response to rAAV-shRNA, allowing for safer and more robust therapeutic gene knockdown, and gives us insight into the basic functions of muscle microRNAs.

ORGANISM(S): Mus musculus

PROVIDER: GSE129896 | GEO | 2019/12/30

REPOSITORIES: GEO

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Project description:Heart failure is associated with high morbidity and mortality and its incidence increases worldwide. MicroRNAs (miRNAs) are potential markers and targets for diagnostic and therapeutic applications, respectively. We determined myocardial and circulating miRNA abundance and its changes in patients with stable and end-stage heart failure before and at different time points after mechanical unloading by a left ventricular assist device (LVAD) by small-RNA-sequencing. MiRNA changes in failing heart tissues partially resembled that of fetal myocardium. Consistent with prototypical miRNAM-bM-^@M-^Starget-mRNA interactions, target mRNA levels were negatively correlated to changes in abundance for highly expressed miRNAs in heart failure and fetal hearts. The circulating small RNA profile was dominated by miRNAs, and fragments of tRNAs and small cytoplasmic RNAs. Heart- and muscle-specific circulating miRNAs (myomirs) increased up to 140-fold in advanced heart failure, which coincided with a similar increase in cardiac troponin I protein, the established marker for heart injury. These extracellular changes nearly completely reversed 3 months following initiation of LVAD support. In stable heart failure, circulating miRNAs showed less than 5-fold differences compared to normal, and myomir and cardiac troponin I levels were only captured near the detection limit. These findings provide the underpinning for miRNA-based therapies and emphasize the usefulness of circulating miRNAs as biomarkers for heart injury performing similar to established diagnostic protein biomarkers. Total RNA isolated from human left ventricular myocardium of failing hearts due to dilated or ischemic cardiomyopathy before and after mechanical unloading by a left ventricular assist device, and fetal myocardium compared to non-failing postnatal myocardium was subjected to multiplexed small RNA-sequencing on the Illumina platform. mRNA gene expression data using Illumina HumanHT-12v4 beadarrays for a subset of the myocardial samples is available (GSE52601).

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Small RNA sequencing of mouse muscle and heart samples after small hairpin RNA delivery

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