Non-coding RNAs (ncRNAs) constitute a diverse group of RNA molecules that do not encode protein. They encompass classical ncRNA molecules with structural and/or catalytic roles in translation and mRNA splicing (rRNA, tRNA and snRNA) as well as guides (snoRNAs) of post-transcriptional modifications of other RNAs. Recently, the discovery of new classes of ncRNAs has added new dimensions to the important functions of classically known groups of ncRNA molecules.
Small RNAs have been found to be key elements in eukaryotic and prokaryotic gene regulation, and are of fundamental importance for epigenetic processes that constribute to genome stability in eukaryotes. In addition, the functions of large catalogs of eukaryotic long ncRNAs in chromatin regulation, splicing and mRNA stability are only now beginning to be uncovered. These functions of small and long ncRNAs not only provide deep new insights into how cells function at the molecular level, they also start to show clear links to human non-infectious and infectious diseases. The ncRNA field is, therefore, attractive for research aimed at a fundamental understanding of biological systems as well as research with a specific biotechnological and pharmaceutical goals.