Evaluation of PDE5A and PDE9A Inhibition Impacts on Cardiac microRNA Expression in a Mouse Pressure-Overload-Induced Heart Failure Model

Purpose: This study aimed to determine how two drugs, both ultimately activating the same effector kinase, may differentially modulate microRNAs in a mouse model of cardiac pressure-overload-induced heart failure. Methods: C57Bl/6J mice were subjected to sham or TAC surgeries to induce cardiac pressure-overload and subsequent heart failure. After one week, treatment with either a PDE5A inhibitor (PDE5A-I) or PDE9A inhibitor (PDE9A-I) was initiated and continued for 4 weeks, with cardiac functional measurements to assess treatment efficacy occurring weekly. At 5 weeks after surgery, mice were sacrificed and myocardium collected. Left ventricular myocardium was used for RNA isolation and subsequent microRNA sequencing on an Illumina HS2500. Data was analyzed using the miRge program (v1.0), which utilizes CutAdapt 1.8 to pre-process sequencing data and Bowtie 1.1.1 to perform read alignments, to generate miRNA counts and reads-per-million data. Count data was further analyzed for differential expression using Bioconductor's DESeq package (v1.26.0). Results and Conclusions: Our study details how two treatments, both targeting the same kinase and with similar phenotypic improvements, result in profoundly different miRNA expression profiles. We found that PDE5A inhibition greatly decreased microRNA expression as compared to heart failure controls, whereas PDE9A inhibition changed virtually no microRNAs in comparison. Our results illustrate how cellular compartmentalization of enzymes can play a significant role in microRNA modulation, as well as a disconnect between phenotypic outcome and microRNA profile, despite treatments impacting the same effector kinase and being equally effective in ameliorating disease. Myocardial microRNA profiles were generated for C57Bl6/J mice subjected to cardiac pressure-overload or sham surgeries, and concomitantly treated with either a PDE5A or PDE9A inhibitor. Sequencing was performed on an Illumina HiSeq 2500 with an n of 5-6 per group.