miRNA

A microRNA (abbreviated miRNA) is a short ribonucleic acid (RNA) molecule found in eukaryotic cells. A microRNA molecule has very few nucleotides (an average of 22) compared with other RNAs.

miRNAs are post-transcriptional regulators that bind to complementary sequences on target messenger RNA transcripts (mRNAs), usually resulting in translational repression or target degradation and gene silencing. The human genome may encode over 1000 miRNAs.

The first miRNAs were characterized in the early 1990s. However, miRNAs were not recognized as a distinct class of biological regulators with conserved functions until the early 2000s.