Non-Canonical MicroRNA Biogenesis and Function
Thomas C. Roberts and Matthew J.A. Wood
from: Applied RNAi: From Fundamental Research to Therapeutic Applications (Edited by: Patrick Arbuthnot and Marc S. Weinberg). Caister Academic Press, U.K. (2014)
MicroRNAs (miRNAs) are small, single-stranded non-coding RNAs that act primarily as post-transcriptional negative regulators of gene expression and are implicated in a wide range of cellular processes and pathological conditions. As such, miRNAs are being investigated both as disease biomarkers and as novel therapeutic targets for the treatment of a plethora of disease conditions including cancers, viral infections and genetic disorders. Here we consider non-canonical processing and functions of miRNAs. Alternative sources of miRNAs are described including Dicer-negative miRNAs, mirtrons, endo-shRNAs as well as miRNAs derived from snoRNAs and tRNAs. Non-miRNA small RNA biogenesis pathways are also briefly discussed including piRNAs, endo-siRNAs and tiRNAs. In addition, we discuss the causes and consequences of heterogeneity in processing and post-transcriptional editing of miRNAs. Lastly, we consider non-canonical miRNA functions including miRNAs that activate translation or regulate gene expression at the epigenetic level, interactions between miRNAs and long non-coding RNAs (lncRNAs), regulation of miRNA activity by endogenous miRNA sponges, and the role of miRNAs in the extracellular environment read more ...