Abstract 14003: Novel Role of microRNA (miR)-451 in Modulation of Oxidative Stress and Kinase Signaling in Mouse Myocardium
Oxidative stress is a key factor in the development of multiple cardiac diseases. Elevation of myocardial reactive oxygen species (ROS) level was due to either activation of ROS generators or inhibition of antioxidants expression. miR-451 was known to regulate erythrocytes differentiation and also reported to regulate the cardioprotective effect of ischemic preconditioning. However, the relationship between myocardial miR-451 expression and cardiac oxidative stress is currently unknown. We hypothesized that miR-451 is a novel modulator of the myocardial ROS level via the expression of certain antioxidants and activation of their pathways in the heart. In our studies, the perfused wild-type (WT) and miR-451 knockout (KO) mice hearts were homogenized and the myocardial ROS level was determined by H2DCF-DA staining. The fluorescent signal of ROS in each myocardium sample was determined continuously for up to 1 hr. The miR-451 KO myocardium showed significant (p=0.02, n=3) increase of ROS production vs. that of the WT, suggesting that KO miR-451 increases myocardial oxidative stress. We also screened the mRNA expression of oxidative stress-related genes using real-time PCR. Although the expression of the ROS generator NADPH oxidase subunits gp91phox, p67phox and p47phox, was not different between the KO and WT hearts, the antioxidant gene NF-E2 related factor-2 (Nrf2) mRNA was found significantly decreased in the KO hearts (24% ↓ vs. WT, p=0.02, n=3). The decrease of Nrf2 mRNA in KO heart was confirmed by its protein expression using Western blot (66% ↓ vs. WT, n=3). To further investigate the potential upstream kinase cascades of Nrf2 expression, phosphorylation (p) of AMPK and ERK1/2 kinases was determined, which was found both significantly decreased in the KO hearts (76% ↓ in p-AMPK vs. WT, p=0.015, n=3; and 65.2% ↓ in p-ERK vs. WT, p=0.022, n=3). In contrast, the protein expression levels of the total AMPK and ERK1/2 were not different between the WT and KO hearts. Taken together, our data show that miR-451 regulates the Nrf2 expression and activation of AMPK and ERK1/2 kinases in the heart. miR-451 may play a novel protective role against myocardial oxidative stress via the modulation of the expression of antioxidants and activation of certain kinase pathways.
- © 2013 by American Heart Association, Inc.