The long and the short of noncoding RNAs.

Controlling protein-coding gene expression can no longer be attributed purely to proteins involved in transcription, RNA processing, and translation. The role that noncoding RNAs (ncRNAs) play as potent and specific regulators of gene expression is now widely recognized in almost all species studied to date. Long ncRNAs can both upregulate and downregulate gene expression in both eukaryotes and prokaryotes and are essential in processes such as dosage compensation, genomic imprinting, developmental patterning and differentiation, and stress response. Small ncRNAs also play essential roles in diverse organisms, although are limited to eukaryotes. Different small RNA classes regulate diverse processes such as transposon and virus suppression, as well as many key developmental processes.