Role reversal: The regulation of neuronal gene expression by microRNAs

In a similar fashion to transcription factors, non-coding RNAs can be essential regulators of gene expression. The largest class of non-coding RNAs is the microRNAs. These ∼22 nt double-stranded RNA molecules can repress translation or target mRNA degradation. There has been a surge of research in the past year stimulated by the recent availability of specialized techniques, both in vitro and in silico, for predicting and characterizing microRNAs. The accumulating evidence suggests that microRNAs are ubiquitous regulators of gene expression during development. The combined actions of microRNAs and transcription factors are able to tune the expression of proteins on a global level in a manner that cannot be achieved by transcription factors alone.