MicroRNAs in cardiac diseases: The devil is in the details

Since their discovery in 1993, it has become clear that microRNAs (miRNAs) constitute a completely new layer of gene regulation. MiRNAs are ~22 nucleotide long, non-coding RNA sequences that regulate gene expression by binding to the 3’UTR of messenger RNAs (mRNAs), resulting in repression of translation into protein. Many miRNAs show specific expression patterns and their level of expression is influenced by physiological and pathological conditions. In this thesis we investigated miRNAs in three aspects of cardiac biology. In the first part we studied the biological role of three specific miRNAs (i.e. miR-30c, miR-133 and miR-15) in cardiac hypertrophy and heart failure. In the second part of this thesis, we reveal the contribution of miRNAs to disease severity in patients with long QT syndrome, and in the third part we investigated whether miRNAs in plasma can be used as diagnostic biomarkers for heart failure.