Control of RNA silencing and localization by endolysosomes

Recent advances in the cell biology of RNA silencing have unraveled an intriguing association of post-transcriptionally regulated RNA with endolysosomal membranes in several circumstances of mRNA localization, microRNA activity and viral RNA transport and packaging. Endolysosomal membranes are a nexus of communication and transport between cells and their exterior environment for signaling receptors, pathogens and nutrients. Here, we discuss recent data that support a view that endolysosomal positioning of RNA might facilitate intercellular transmission of RNA and host defence against viruses and retrotransposons. Positioning of RNA regulatory mechanisms on endolysosomal membranes might permit rapid and localized control of microRNA (miRNA) gene regulatory programs and mRNA translation in response to environmental signals, such as activated plasma membrane receptors transported on endosomes. Finally, we suggest that the pathology of several conditions, including Huntington's disease, might be a consequence of the disruption of the control of RNA via endolysosomal membranes.