MicroRNAs and neuronal development.

The importance of the involvement of non-protein coding RNAs in biological processes has become evident in recent years along with the identification of the transcriptional regulatory mechanisms that allow them to exert their roles. MicroRNAs (miRNAs) are a novel class of small non-coding RNA that regulates messenger RNA abundance. The capacity of each miRNA to target several transcripts suggests an ability to build a complex regulatory network for fine tuning gene expression; a mechanism by which they are thought to regulate cell fate, proliferation and identity. The brain expresses more distinct miRNAs than any other tissue in vertebrates and it presents an impressive variety of cell types, including many different classes of neurons. Here we review more than 10 years of miRNA research, and discuss the most important findings that have established miRNAs as key regulators of neuronal development.