Dual MicroRNA Blockade Increases Expression of Antioxidant Protective Proteins: Implications for Ischemia-Reperfusion Injury

Background. MicroRNAs (miRNAs) are short noncoding RNAs which each cause repression of many target genes. Previous work has demonstrated that therapeutic blockade of single miRNAs is possible. miR-24-3p and miR-145-5p are reported to have a detrimental role in ischemia-reperfusion injury. As the action of miRNAs is inhibitory, we hypothesized that dual blockade of both miRNAs could synergistically upregulate shared target genes. Methods. Quantification of miRNA expression in donated kidneys was performed using polymerase chain reaction (PCR) panels. Ischemia-reperfusion injury was modeled in vitro by placing human umbilical vein endothelial cells into a hypoxic incubator (1% O-2) for 24 hours, with reoxygenation for 6 hours. RNA expression was quantified with reverse transcription quantitative polymerase chain reaction and protein expression assessed with Western blot. Antisense oligonucleotides were used to inhibit miRNAs. Results. miR-24-3p and miR-145-5p were highly expressed in human kidneys following extended cold ischemia. In vitro, hypoxia caused significant upregulation of miR-24-3p (P <= 0.001) and miR-145-5p (P <= 0.001) and significant downregulation in messenger RNA of shared targets superoxide dismutase 2 (P <= 0.001) and heme oxygenase 1 (P <= 0.001). These changes were mirrored at the protein level. Dual inhibition of both miR-24-3p and miR-145-5p caused significant upregulation of superoxide dismutase 2 and heme oxygenase 1 protein following hypoxia-reoxygenation; fold change of 3.17 (P <= 0.05) and 6.97 (P <= 0.05) respectively. Dual inhibition resulted in reduced cellular reactive oxygen species production compared with negative control (P <= 0.05) and single blockade of miR-24-3p (P <= 0.01) or miR-145-5p (P <= 0.05). Conclusions. Dual blockade of 2 miRNAs can act synergistically to increase the expression of shared gene targets. Dual blockade of miR-24-3p and miR-145-5p represents a novel therapeutic option worthy of further research.