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The impact of small RNAs
Author(s) -
Obernosterer Gregor,
Meister Gunter,
Poy Matthew N,
Kuras Annerose
Publication year - 2007
Publication title -
embo reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.584
H-Index - 184
eISSN - 1469-3178
pISSN - 1469-221X
DOI - 10.1038/sj.embor.7400874
Subject(s) - bohr model , library science , classics , art history , history , physics , computer science , quantum mechanics
Our understanding of the RNA‐mediated gene‐regulatory pathway, known as RNA interference (RNAi), has come a long way since its discovery in the early 1990s. At that time, all knowledge of RNA‐mediated silencing was based on one phenomenon: the loss of a non‐lethal phenotype after the introduction of exogenous RNA into the affected organism. Since then, various families of non‐coding RNAs (ncRNAs) that exhibit analogous repressive effects on gene expression have been identified in most eukaryotic genomes (Cogoni et al , 1996; Jorgensen, 2003). Among these are small‐interfering RNAs (siRNAs), microRNAs (miRNAs), repeat‐associated small‐interfering RNAs (rasiRNAs) and scanRNAs (scnRNAs; Mochizuki & Gorovsky, 2004; Tomari & Zamore, 2005). All of these silencing triggers are 21–28 nucleotides in length and assemble into similar RNA‐silencing effector complexes; however, they can be distinguished by their mode of inception. siRNAs can be exogenous (derived from viruses) or endogenous (derived from long double‐stranded RNA (dsRNA) transcripts) in origin, whereas miRNAs, rasiRNAs and scnRNAs originate exclusively from endogenous sources. The members of the miRNA family of ncRNAs are of special relevance because of their role in development and cell differentiation.The processing of ncRNAs into mature 21–28 nucleotide RNA duplexes occurs either through the initial processing of the long RNA precursor by the RNase III‐like endonuclease Drosha followed by a final maturation step effected by the ribonuclease III enzyme Dicer, or directly by the latter in a one‐step splicing event. Once processed, the RNA‐silencing trigger is loaded into one of many RNAi effector complexes, all of which share a common component: a member of the RNase H family of proteins called Argonaute (Ago). The final ribonucleoprotein effector complexes function by either repressing gene expression through interacting with a cognate messenger RNA (mRNA) or effecting genome rearrangement (Meister & Tuschl, 2004; Mochizuki & Gorovsky, 2004).The …