Role of the specific miRNAs on the reactive oxygen species stimulated cardiomyocytes

Abstract

Oxidative damage has been suggested to play a critical role in pathophysiology of various cardiovascular diseases. A staggering amount of evidences implicates that reactive oxygen species (ROS) is a common denominator in the development of most cardiovascular diseases. It has been reported that miRNAs play important roles in physiological regulation of cardiac biology as well as in pathological events such as hypertrophy, apoptosis, and heart failure. However, the study on microRNAs in ROS-induced cardiac apoptosis and hypertrophy has been rarely carried out. ROS regulates two face of cardiac myocyte phenotype: hypertrophy occurred at low levels (30 μM) and apoptosis occurred at higher levels (100–150 μM) of hydrogen peroxide (H2O2) in primary cultured neonatal rat cardiomyocytes. Hypertrophy was determined by significant (30%) increase of cell size and hypertrophic markers, including α-MHC, MLC, NFATC1, ANP and BNP, and apoptosis was measured by cell viability, Annexin V / PI staining, and caspase-3 activity. In this study, miRNAs that are involved in ROS-mediated regulation of cardiomyocyte phenotype were elucidated. A set of miRNAs (miR-1, 26a, 1331, and 145) were identified to abound in cardiomyocytes. These miRNAs were abundantly expressed in neonatal and adult heart tissue. Moreover, H2O2-mediated up-regulation and down-regulation of specific miRNAs was confirmed and their regulation by H2O2 were determined. At a concentration of H2O2 that caused hypertrophy (30 μM) the expression of miR-1 was decreased and overexpression of miR-1 inhibited H2O2-induced hypertrophy. At a concentration of H2O2 that caused apoptosis (100 μM) miR-26a expression was increased while miR-26a mimic enhanced H2O2 -induced apoptosis. The results indicate that different spectrums of miRNAs affect H2O2-mediated cardiomyocyte hypertrophy and apoptosis.