Abstract 14856: In vivo Regulation of PDE-1A and cGMP by miRNA-21 in Mouse Heart
Background: Phosphodiesterase (PDE)-1A regulates an important intracellular second messenger, cyclic guanosine monophosphate (cGMP), and thus maintains cardiomyocyte homeostasis. Surprisingly, the role of PDE-1A in cardiac ischemia/reperfusion has never been reported so far. We previously demonstrated that intramyocardial administration of synthetic microRNA-21 (miRNA-21) protected mouse hearts against ischemia/reperfusion injury (I/R). The purpose of this study was to examine whether miRNA-21 exerts its cardioprotective effects against I/R by targeting PDE-1A and preserving cGMP.
Methods & Results: Chemically synthesized and purified miRNA-21 or scrambled miRNA was treated with a transfect agent, NeoFX, to facilitate its entry into cardiac cells. The miRNA-NeoFX complexes were then administered to CD-1 mice by multi-site intramyocardial injections (2 μg / heart). 24 hours later, the hearts were harvested for assessment of PDE-1A mRNA and protein using qPCR and Western Blot, respectively. cGMP was measured using enzyme linked immunosorbent assay. miRNA-21 treatment down-regulated PDE-1A mRNA expression by 47.4% (p<0.023) as compared to the scrambled miRNA treatment. Western blot analysis also confirmed that PDE-1A protein expression was suppressed by 89.1% (p<0.001) in miRNA-21 group versus scrambled miRNA group (Figure). Furthermore, cGMP level in the miRNA-21 group was increased by 97.5% (p<0.015) as compared to the scrambled miRNA group. There was no difference in cAMP level between the two groups.
CONCLUSION: miRNA-21 down-regulates PDE-1A thereby increasing cGMP, which may potentially mediate its cardioprotective effect against I/R injury. This study provides a promising innovative aspect of miRN-21 in regulation of PDE-1A.
- © 2012 by American Heart Association, Inc.