Circulating MicroRNAs in cardiovascular disease.

MicroRNAs (miRNAs) are short, single-stranded, noncoding, highly conserved posttranscriptional regulators found in a variety of tissues including circulating blood.1 MicroRNAs regulate gene expression posttranscriptionally through inhibiting translation from and/or inducing degradation of specific RNAs.2 Certain miRNAs are expressed and function cell-type specifically or in association with particular physiological processes. MicroRNAs contribute to cardiac development and remodeling, and miRNAs found in cardiac tissue show dynamic changes in the setting of heart disease, suggesting their involvement in the regulation of cardiovascular disease (CVD). Mouse and human studies have emphasized the importance of individual miRNAs in different forms of CVD, including myocardial infarction (mirR-1, miR-133a, miR-208a, and miR-499), atrial and ventricular arrhythmias (miR-1, miR-133, and miR-328), fibrosis (miR-21 and miR29), and ventricular hypertrophy (miR-208 and miR-133).3–7