Non-coding RNAs

Non-coding RNAs (ncRNAs) have emerged recently as important players in a plethora of cellular processes in health and disease. Since the 1950s, after transfer RNAs and ribosomal RNAs were discovered, a tremendous increase in studies concerning the ncRNA world has followed. Several types of ncRNAs can be distinguished: housekeeping (rRNAs and tRNAs) and regulatory RNAs. Major classes of regulatory ncRNAs include long ncRNAs (lncRNA), enhancer RNAs (eRNA), circular RNAs (circRNA), and small ncRNAs such as microRNA (miRNA), small nucleolar RNA (snoRNA), small nuclear RNA (snRNA), PIWI-interacting RNA (piRNA), and tRNA-derived fragments (tRFs). Mechanistically, ncRNAs can interact with various molecules (DNA, RNA, proteins) and act at several levels from chromatin accessibility, through transcription to translation. In this chapter, we provide an overview of the diverse mechanisms of action for particular classes of ncRNAs behind the regulation of cellular pathways.